<?php
/**
 * Main WordPress API
 *
 * @package WordPress
 */

require( ABSPATH . WPINC . '/option.php' );

/**
 * Convert given date string into a different format.
 *
 * $format should be either a PHP date format string, e.g. 'U' for a Unix
 * timestamp, or 'G' for a Unix timestamp assuming that $date is GMT.
 *
 * If $translate is true then the given date and format string will
 * be passed to date_i18n() for translation.
 *
 * @since 0.71
 *
 * @param string $format    Format of the date to return.
 * @param string $date      Date string to convert.
 * @param bool   $translate Whether the return date should be translated. Default true.
 * @return string|int|bool Formatted date string or Unix timestamp. False if $date is empty.
 */
function mysql2date( $format, $date, $translate = true ) {
    if ( empty( $date ) )
        return false;

    if ( 'G' == $format )
        return strtotime( $date . ' +0000' );

    $i = strtotime( $date );

    if ( 'U' == $format )
        return $i;

    if ( $translate )
        return date_i18n( $format, $i );
    else
        return date( $format, $i );
}

/**
 * Retrieve the current time based on specified type.
 *
 * The 'mysql' type will return the time in the format for MySQL DATETIME field.
 * The 'timestamp' type will return the current timestamp.
 * Other strings will be interpreted as PHP date formats (e.g. 'Y-m-d').
 *
 * If $gmt is set to either '1' or 'true', then both types will use GMT time.
 * if $gmt is false, the output is adjusted with the GMT offset in the WordPress option.
 *
 * @since 1.0.0
 *
 * @param string   $type Type of time to retrieve. Accepts 'mysql', 'timestamp', or PHP date
 *                       format string (e.g. 'Y-m-d').
 * @param int|bool $gmt  Optional. Whether to use GMT timezone. Default false.
 * @return int|string Integer if $type is 'timestamp', string otherwise.
 */
function current_time( $type, $gmt = 0 ) {
    switch ( $type ) {
        case 'mysql':
            return ( $gmt ) ? gmdate( 'Y-m-d H:i:s' ) : gmdate( 'Y-m-d H:i:s', ( time() + ( get_option( 'gmt_offset' ) * HOUR_IN_SECONDS ) ) );
        case 'timestamp':
            return ( $gmt ) ? time() : time() + ( get_option( 'gmt_offset' ) * HOUR_IN_SECONDS );
        default:
            return ( $gmt ) ? date( $type ) : date( $type, time() + ( get_option( 'gmt_offset' ) * HOUR_IN_SECONDS ) );
    }
}

/**
 * Retrieve the date in localized format, based on timestamp.
 *
 * If the locale specifies the locale month and weekday, then the locale will
 * take over the format for the date. If it isn't, then the date format string
 * will be used instead.
 *
 * @since 0.71
 *
 * @global WP_Locale $wp_locale
 *
 * @param string   $dateformatstring Format to display the date.
 * @param bool|int $unixtimestamp    Optional. Unix timestamp. Default false.
 * @param bool     $gmt              Optional. Whether to use GMT timezone. Default false.
 *
 * @return string The date, translated if locale specifies it.
 */
function date_i18n( $dateformatstring, $unixtimestamp = false, $gmt = false ) {
    global $wp_locale;
    $i = $unixtimestamp;

    if ( false === $i ) {
        $i = current_time( 'timestamp', $gmt );
    }

    /*
     * Store original value for language with untypical grammars.
     * See https://core.trac.wordpress.org/ticket/9396
     */
    $req_format = $dateformatstring;

    if ( ( !empty( $wp_locale->month ) ) && ( !empty( $wp_locale->weekday ) ) ) {
        $datemonth = $wp_locale->get_month( date( 'm', $i ) );
        $datemonth_abbrev = $wp_locale->get_month_abbrev( $datemonth );
        $dateweekday = $wp_locale->get_weekday( date( 'w', $i ) );
        $dateweekday_abbrev = $wp_locale->get_weekday_abbrev( $dateweekday );
        $datemeridiem = $wp_locale->get_meridiem( date( 'a', $i ) );
        $datemeridiem_capital = $wp_locale->get_meridiem( date( 'A', $i ) );
        $dateformatstring = ' '.$dateformatstring;
        $dateformatstring = preg_replace( "/([^\\\])D/", "\\1" . backslashit( $dateweekday_abbrev ), $dateformatstring );
        $dateformatstring = preg_replace( "/([^\\\])F/", "\\1" . backslashit( $datemonth ), $dateformatstring );
        $dateformatstring = preg_replace( "/([^\\\])l/", "\\1" . backslashit( $dateweekday ), $dateformatstring );
        $dateformatstring = preg_replace( "/([^\\\])M/", "\\1" . backslashit( $datemonth_abbrev ), $dateformatstring );
        $dateformatstring = preg_replace( "/([^\\\])a/", "\\1" . backslashit( $datemeridiem ), $dateformatstring );
        $dateformatstring = preg_replace( "/([^\\\])A/", "\\1" . backslashit( $datemeridiem_capital ), $dateformatstring );

        $dateformatstring = substr( $dateformatstring, 1, strlen( $dateformatstring ) -1 );
    }
    $timezone_formats = array( 'P', 'I', 'O', 'T', 'Z', 'e' );
    $timezone_formats_re = implode( '|', $timezone_formats );
    if ( preg_match( "/$timezone_formats_re/", $dateformatstring ) ) {
        $timezone_string = get_option( 'timezone_string' );
        if ( $timezone_string ) {
            $timezone_object = timezone_open( $timezone_string );
            $date_object = date_create( null, $timezone_object );
            foreach ( $timezone_formats as $timezone_format ) {
                if ( false !== strpos( $dateformatstring, $timezone_format ) ) {
                    $formatted = date_format( $date_object, $timezone_format );
                    $dateformatstring = ' '.$dateformatstring;
                    $dateformatstring = preg_replace( "/([^\\\])$timezone_format/", "\\1" . backslashit( $formatted ), $dateformatstring );
                    $dateformatstring = substr( $dateformatstring, 1, strlen( $dateformatstring ) -1 );
                }
            }
        }
    }
    $j = @date( $dateformatstring, $i );

    /**
     * Filters the date formatted based on the locale.
     *
     * @since 2.8.0
     *
     * @param string $j          Formatted date string.
     * @param string $req_format Format to display the date.
     * @param int    $i          Unix timestamp.
     * @param bool   $gmt        Whether to convert to GMT for time. Default false.
     */
    $j = apply_filters( 'date_i18n', $j, $req_format, $i, $gmt );
    return $j;
}

/**
 * Determines if the date should be declined.
 *
 * If the locale specifies that month names require a genitive case in certain
 * formats (like 'j F Y'), the month name will be replaced with a correct form.
 *
 * @since 4.4.0
 *
 * @param string $date Formatted date string.
 * @return string The date, declined if locale specifies it.
 */
function wp_maybe_decline_date( $date ) {
    global $wp_locale;

    // i18n functions are not available in SHORTINIT mode
    if ( ! function_exists( '_x' ) ) {
        return $date;
    }

    /* translators: If months in your language require a genitive case,
     * translate this to 'on'. Do not translate into your own language.
     */
    if ( 'on' === _x( 'off', 'decline months names: on or off' ) ) {
        // Match a format like 'j F Y' or 'j. F'
        if ( @preg_match( '#^\d{1,2}\.? [^\d ]+#u', $date ) ) {
            $months          = $wp_locale->month;
            $months_genitive = $wp_locale->month_genitive;

            foreach ( $months as $key => $month ) {
                $months[ $key ] = '# ' . $month . '( |$)#u';
            }

            foreach ( $months_genitive as $key => $month ) {
                $months_genitive[ $key ] = ' ' . $month . '$1';
            }

            $date = preg_replace( $months, $months_genitive, $date );
        }
    }

    // Used for locale-specific rules
    $locale = get_locale();

    if ( 'ca' === $locale ) {
        // " de abril| de agost| de octubre..." -> " d'abril| d'agost| d'octubre..."
        $date = preg_replace( '# de ([ao])#i', " d'\\1", $date );
    }

    return $date;
}

/**
 * Convert float number to format based on the locale.
 *
 * @since 2.3.0
 *
 * @global WP_Locale $wp_locale
 *
 * @param float $number   The number to convert based on locale.
 * @param int   $decimals Optional. Precision of the number of decimal places. Default 0.
 * @return string Converted number in string format.
 */
function number_format_i18n( $number, $decimals = 0 ) {
    global $wp_locale;

    if ( isset( $wp_locale ) ) {
        $formatted = number_format( $number, absint( $decimals ), $wp_locale->number_format['decimal_point'], $wp_locale->number_format['thousands_sep'] );
    } else {
        $formatted = number_format( $number, absint( $decimals ) );
    }

    /**
     * Filters the number formatted based on the locale.
     *
     * @since  2.8.0
     *
     * @param string $formatted Converted number in string format.
     */
    return apply_filters( 'number_format_i18n', $formatted );
}

/**
 * Convert number of bytes largest unit bytes will fit into.
 *
 * It is easier to read 1 KB than 1024 bytes and 1 MB than 1048576 bytes. Converts
 * number of bytes to human readable number by taking the number of that unit
 * that the bytes will go into it. Supports TB value.
 *
 * Please note that integers in PHP are limited to 32 bits, unless they are on
 * 64 bit architecture, then they have 64 bit size. If you need to place the
 * larger size then what PHP integer type will hold, then use a string. It will
 * be converted to a double, which should always have 64 bit length.
 *
 * Technically the correct unit names for powers of 1024 are KiB, MiB etc.
 *
 * @since 2.3.0
 *
 * @param int|string $bytes    Number of bytes. Note max integer size for integers.
 * @param int        $decimals Optional. Precision of number of decimal places. Default 0.
 * @return string|false False on failure. Number string on success.
 */
function size_format( $bytes, $decimals = 0 ) {
    $quant = array(
        'TB' => TB_IN_BYTES,
        'GB' => GB_IN_BYTES,
        'MB' => MB_IN_BYTES,
        'KB' => KB_IN_BYTES,
        'B'  => 1,
    );

    if ( 0 === $bytes ) {
        return number_format_i18n( 0, $decimals ) . ' B';
    }

    foreach ( $quant as $unit => $mag ) {
        if ( doubleval( $bytes ) >= $mag ) {
            return number_format_i18n( $bytes / $mag, $decimals ) . ' ' . $unit;
        }
    }

    return false;
}

/**
 * Get the week start and end from the datetime or date string from MySQL.
 *
 * @since 0.71
 *
 * @param string     $mysqlstring   Date or datetime field type from MySQL.
 * @param int|string $start_of_week Optional. Start of the week as an integer. Default empty string.
 * @return array Keys are 'start' and 'end'.
 */
function get_weekstartend( $mysqlstring, $start_of_week = '' ) {
    // MySQL string year.
    $my = substr( $mysqlstring, 0, 4 );

    // MySQL string month.
    $mm = substr( $mysqlstring, 8, 2 );

    // MySQL string day.
    $md = substr( $mysqlstring, 5, 2 );

    // The timestamp for MySQL string day.
    $day = mktime( 0, 0, 0, $md, $mm, $my );

    // The day of the week from the timestamp.
    $weekday = date( 'w', $day );

    if ( !is_numeric($start_of_week) )
        $start_of_week = get_option( 'start_of_week' );

    if ( $weekday < $start_of_week )
        $weekday += 7;

    // The most recent week start day on or before $day.
    $start = $day - DAY_IN_SECONDS * ( $weekday - $start_of_week );

    // $start + 1 week - 1 second.
    $end = $start + WEEK_IN_SECONDS - 1;
    return compact( 'start', 'end' );
}

/**
 * Unserialize value only if it was serialized.
 *
 * @since 2.0.0
 *
 * @param string $original Maybe unserialized original, if is needed.
 * @return mixed Unserialized data can be any type.
 */
function maybe_unserialize( $original ) {
    if ( is_serialized( $original ) ) // don't attempt to unserialize data that wasn't serialized going in
        return @unserialize( $original );
    return $original;
}

/**
 * Check value to find if it was serialized.
 *
 * If $data is not an string, then returned value will always be false.
 * Serialized data is always a string.
 *
 * @since 2.0.5
 *
 * @param string $data   Value to check to see if was serialized.
 * @param bool   $strict Optional. Whether to be strict about the end of the string. Default true.
 * @return bool False if not serialized and true if it was.
 */
function is_serialized( $data, $strict = true ) {
    // if it isn't a string, it isn't serialized.
    if ( ! is_string( $data ) ) {
        return false;
    }
    $data = trim( $data );
    if ( 'N;' == $data ) {
        return true;
    }
    if ( strlen( $data ) < 4 ) {
        return false;
    }
    if ( ':' !== $data[1] ) {
        return false;
    }
    if ( $strict ) {
        $lastc = substr( $data, -1 );
        if ( ';' !== $lastc && '}' !== $lastc ) {
            return false;
        }
    } else {
        $semicolon = strpos( $data, ';' );
        $brace     = strpos( $data, '}' );
        // Either ; or } must exist.
        if ( false === $semicolon && false === $brace )
            return false;
        // But neither must be in the first X characters.
        if ( false !== $semicolon && $semicolon < 3 )
            return false;
        if ( false !== $brace && $brace < 4 )
            return false;
    }
    $token = $data[0];
    switch ( $token ) {
        case 's' :
            if ( $strict ) {
                if ( '"' !== substr( $data, -2, 1 ) ) {
                    return false;
                }
            } elseif ( false === strpos( $data, '"' ) ) {
                return false;
            }
        // or else fall through
        case 'a' :
        case 'O' :
            return (bool) preg_match( "/^{$token}:[0-9]+:/s", $data );
        case 'b' :
        case 'i' :
        case 'd' :
            $end = $strict ? '$' : '';
            return (bool) preg_match( "/^{$token}:[0-9.E-]+;$end/", $data );
    }
    return false;
}

/**
 * Check whether serialized data is of string type.
 *
 * @since 2.0.5
 *
 * @param string $data Serialized data.
 * @return bool False if not a serialized string, true if it is.
 */
function is_serialized_string( $data ) {
    // if it isn't a string, it isn't a serialized string.
    if ( ! is_string( $data ) ) {
        return false;
    }
    $data = trim( $data );
    if ( strlen( $data ) < 4 ) {
        return false;
    } elseif ( ':' !== $data[1] ) {
        return false;
    } elseif ( ';' !== substr( $data, -1 ) ) {
        return false;
    } elseif ( $data[0] !== 's' ) {
        return false;
    } elseif ( '"' !== substr( $data, -2, 1 ) ) {
        return false;
    } else {
        return true;
    }
}

/**
 * Serialize data, if needed.
 *
 * @since 2.0.5
 *
 * @param string|array|object $data Data that might be serialized.
 * @return mixed A scalar data
 */
function maybe_serialize( $data ) {
    if ( is_array( $data ) || is_object( $data ) )
        return serialize( $data );

    // Double serialization is required for backward compatibility.
    // See https://core.trac.wordpress.org/ticket/12930
    // Also the world will end. See WP 3.6.1.
    if ( is_serialized( $data, false ) )
        return serialize( $data );

    return $data;
}

/**
 * Retrieve post title from XMLRPC XML.
 *
 * If the title element is not part of the XML, then the default post title from
 * the $post_default_title will be used instead.
 *
 * @since 0.71
 *
 * @global string $post_default_title Default XML-RPC post title.
 *
 * @param string $content XMLRPC XML Request content
 * @return string Post title
 */
function xmlrpc_getposttitle( $content ) {
    global $post_default_title;
    if ( preg_match( '/<title>(.+?)<\/title>/is', $content, $matchtitle ) ) {
        $post_title = $matchtitle[1];
    } else {
        $post_title = $post_default_title;
    }
    return $post_title;
}

/**
 * Retrieve the post category or categories from XMLRPC XML.
 *
 * If the category element is not found, then the default post category will be
 * used. The return type then would be what $post_default_category. If the
 * category is found, then it will always be an array.
 *
 * @since 0.71
 *
 * @global string $post_default_category Default XML-RPC post category.
 *
 * @param string $content XMLRPC XML Request content
 * @return string|array List of categories or category name.
 */
function xmlrpc_getpostcategory( $content ) {
    global $post_default_category;
    if ( preg_match( '/<category>(.+?)<\/category>/is', $content, $matchcat ) ) {
        $post_category = trim( $matchcat[1], ',' );
        $post_category = explode( ',', $post_category );
    } else {
        $post_category = $post_default_category;
    }
    return $post_category;
}

/**
 * XMLRPC XML content without title and category elements.
 *
 * @since 0.71
 *
 * @param string $content XML-RPC XML Request content.
 * @return string XMLRPC XML Request content without title and category elements.
 */
function xmlrpc_removepostdata( $content ) {
    $content = preg_replace( '/<title>(.+?)<\/title>/si', '', $content );
    $content = preg_replace( '/<category>(.+?)<\/category>/si', '', $content );
    $content = trim( $content );
    return $content;
}

/**
 * Use RegEx to extract URLs from arbitrary content.
 *
 * @since 3.7.0
 *
 * @param string $content Content to extract URLs from.
 * @return array URLs found in passed string.
 */
function wp_extract_urls( $content ) {
    preg_match_all(
        "#([\"']?)("
        . "(?:([\w-]+:)?//?)"
        . "[^\s()<>]+"
        . "[.]"
        . "(?:"
        . "\([\w\d]+\)|"
        . "(?:"
        . "[^`!()\[\]{};:'\".,<>«»“”‘’\s]|"
        . "(?:[:]\d+)?/?"
        . ")+"
        . ")"
        . ")\\1#",
        $content,
        $post_links
    );

    $post_links = array_unique( array_map( 'html_entity_decode', $post_links[2] ) );

    return array_values( $post_links );
}

/**
 * Check content for video and audio links to add as enclosures.
 *
 * Will not add enclosures that have already been added and will
 * remove enclosures that are no longer in the post. This is called as
 * pingbacks and trackbacks.
 *
 * @since 1.5.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $content Post Content.
 * @param int    $post_ID Post ID.
 */
function do_enclose( $content, $post_ID ) {
    global $wpdb;

    //TODO: Tidy this ghetto code up and make the debug code optional
    include_once( ABSPATH . WPINC . '/class-IXR.php' );

    $post_links = array();

    $pung = get_enclosed( $post_ID );

    $post_links_temp = wp_extract_urls( $content );

    foreach ( $pung as $link_test ) {
        if ( ! in_array( $link_test, $post_links_temp ) ) { // link no longer in post
            $mids = $wpdb->get_col( $wpdb->prepare("SELECT meta_id FROM $wpdb->postmeta WHERE post_id = %d AND meta_key = 'enclosure' AND meta_value LIKE %s", $post_ID, $wpdb->esc_like( $link_test ) . '%') );
            foreach ( $mids as $mid )
                delete_metadata_by_mid( 'post', $mid );
        }
    }

    foreach ( (array) $post_links_temp as $link_test ) {
        if ( !in_array( $link_test, $pung ) ) { // If we haven't pung it already
            $test = @parse_url( $link_test );
            if ( false === $test )
                continue;
            if ( isset( $test['query'] ) )
                $post_links[] = $link_test;
            elseif ( isset($test['path']) && ( $test['path'] != '/' ) &&  ($test['path'] != '' ) )
                $post_links[] = $link_test;
        }
    }

    /**
     * Filters the list of enclosure links before querying the database.
     *
     * Allows for the addition and/or removal of potential enclosures to save
     * to postmeta before checking the database for existing enclosures.
     *
     * @since 4.4.0
     *
     * @param array $post_links An array of enclosure links.
     * @param int   $post_ID    Post ID.
     */
    $post_links = apply_filters( 'enclosure_links', $post_links, $post_ID );

    foreach ( (array) $post_links as $url ) {
        if ( $url != '' && !$wpdb->get_var( $wpdb->prepare( "SELECT post_id FROM $wpdb->postmeta WHERE post_id = %d AND meta_key = 'enclosure' AND meta_value LIKE %s", $post_ID, $wpdb->esc_like( $url ) . '%' ) ) ) {

            if ( $headers = wp_get_http_headers( $url) ) {
                $len = isset( $headers['content-length'] ) ? (int) $headers['content-length'] : 0;
                $type = isset( $headers['content-type'] ) ? $headers['content-type'] : '';
                $allowed_types = array( 'video', 'audio' );

                // Check to see if we can figure out the mime type from
                // the extension
                $url_parts = @parse_url( $url );
                if ( false !== $url_parts ) {
                    $extension = pathinfo( $url_parts['path'], PATHINFO_EXTENSION );
                    if ( !empty( $extension ) ) {
                        foreach ( wp_get_mime_types() as $exts => $mime ) {
                            if ( preg_match( '!^(' . $exts . ')$!i', $extension ) ) {
                                $type = $mime;
                                break;
                            }
                        }
                    }
                }

                if ( in_array( substr( $type, 0, strpos( $type, "/" ) ), $allowed_types ) ) {
                    add_post_meta( $post_ID, 'enclosure', "$url\n$len\n$mime\n" );
                }
            }
        }
    }
}

/**
 * Retrieve HTTP Headers from URL.
 *
 * @since 1.5.1
 *
 * @param string $url        URL to retrieve HTTP headers from.
 * @param bool   $deprecated Not Used.
 * @return bool|string False on failure, headers on success.
 */
function wp_get_http_headers( $url, $deprecated = false ) {
    if ( !empty( $deprecated ) )
        _deprecated_argument( __FUNCTION__, '2.7.0' );

    $response = wp_safe_remote_head( $url );

    if ( is_wp_error( $response ) )
        return false;

    return wp_remote_retrieve_headers( $response );
}

/**
 * Whether the publish date of the current post in the loop is different from the
 * publish date of the previous post in the loop.
 *
 * @since 0.71
 *
 * @global string $currentday  The day of the current post in the loop.
 * @global string $previousday The day of the previous post in the loop.
 *
 * @return int 1 when new day, 0 if not a new day.
 */
function is_new_day() {
    global $currentday, $previousday;
    if ( $currentday != $previousday )
        return 1;
    else
        return 0;
}

/**
 * Build URL query based on an associative and, or indexed array.
 *
 * This is a convenient function for easily building url queries. It sets the
 * separator to '&' and uses _http_build_query() function.
 *
 * @since 2.3.0
 *
 * @see _http_build_query() Used to build the query
 * @link https://secure.php.net/manual/en/function.http-build-query.php for more on what
 *		 http_build_query() does.
 *
 * @param array $data URL-encode key/value pairs.
 * @return string URL-encoded string.
 */
function build_query( $data ) {
    return _http_build_query( $data, null, '&', '', false );
}

/**
 * From php.net (modified by Mark Jaquith to behave like the native PHP5 function).
 *
 * @since 3.2.0
 * @access private
 *
 * @see https://secure.php.net/manual/en/function.http-build-query.php
 *
 * @param array|object  $data       An array or object of data. Converted to array.
 * @param string        $prefix     Optional. Numeric index. If set, start parameter numbering with it.
 *                                  Default null.
 * @param string        $sep        Optional. Argument separator; defaults to 'arg_separator.output'.
 *                                  Default null.
 * @param string        $key        Optional. Used to prefix key name. Default empty.
 * @param bool          $urlencode  Optional. Whether to use urlencode() in the result. Default true.
 *
 * @return string The query string.
 */
function _http_build_query( $data, $prefix = null, $sep = null, $key = '', $urlencode = true ) {
    $ret = array();

    foreach ( (array) $data as $k => $v ) {
        if ( $urlencode)
            $k = urlencode($k);
        if ( is_int($k) && $prefix != null )
            $k = $prefix.$k;
        if ( !empty($key) )
            $k = $key . '%5B' . $k . '%5D';
        if ( $v === null )
            continue;
        elseif ( $v === false )
            $v = '0';

        if ( is_array($v) || is_object($v) )
            array_push($ret,_http_build_query($v, '', $sep, $k, $urlencode));
        elseif ( $urlencode )
            array_push($ret, $k.'='.urlencode($v));
        else
            array_push($ret, $k.'='.$v);
    }

    if ( null === $sep )
        $sep = ini_get('arg_separator.output');

    return implode($sep, $ret);
}

/**
 * Retrieves a modified URL query string.
 *
 * You can rebuild the URL and append query variables to the URL query by using this function.
 * There are two ways to use this function; either a single key and value, or an associative array.
 *
 * Using a single key and value:
 *
 *     add_query_arg( 'key', 'value', 'http://example.com' );
 *
 * Using an associative array:
 *
 *     add_query_arg( array(
 *         'key1' => 'value1',
 *         'key2' => 'value2',
 *     ), 'http://example.com' );
 *
 * Omitting the URL from either use results in the current URL being used
 * (the value of `$_SERVER['REQUEST_URI']`).
 *
 * Values are expected to be encoded appropriately with urlencode() or rawurlencode().
 *
 * Setting any query variable's value to boolean false removes the key (see remove_query_arg()).
 *
 * Important: The return value of add_query_arg() is not escaped by default. Output should be
 * late-escaped with esc_url() or similar to help prevent vulnerability to cross-site scripting
 * (XSS) attacks.
 *
 * @since 1.5.0
 *
 * @param string|array $key   Either a query variable key, or an associative array of query variables.
 * @param string       $value Optional. Either a query variable value, or a URL to act upon.
 * @param string       $url   Optional. A URL to act upon.
 * @return string New URL query string (unescaped).
 */
function add_query_arg() {
    $args = func_get_args();
    if ( is_array( $args[0] ) ) {
        if ( count( $args ) < 2 || false === $args[1] )
            $uri = $_SERVER['REQUEST_URI'];
        else
            $uri = $args[1];
    } else {
        if ( count( $args ) < 3 || false === $args[2] )
            $uri = $_SERVER['REQUEST_URI'];
        else
            $uri = $args[2];
    }

    if ( $frag = strstr( $uri, '#' ) )
        $uri = substr( $uri, 0, -strlen( $frag ) );
    else
        $frag = '';

    if ( 0 === stripos( $uri, 'http://' ) ) {
        $protocol = 'http://';
        $uri = substr( $uri, 7 );
    } elseif ( 0 === stripos( $uri, 'https://' ) ) {
        $protocol = 'https://';
        $uri = substr( $uri, 8 );
    } else {
        $protocol = '';
    }

    if ( strpos( $uri, '?' ) !== false ) {
        list( $base, $query ) = explode( '?', $uri, 2 );
        $base .= '?';
    } elseif ( $protocol || strpos( $uri, '=' ) === false ) {
        $base = $uri . '?';
        $query = '';
    } else {
        $base = '';
        $query = $uri;
    }

    wp_parse_str( $query, $qs );
    $qs = urlencode_deep( $qs ); // this re-URL-encodes things that were already in the query string
    if ( is_array( $args[0] ) ) {
        foreach ( $args[0] as $k => $v ) {
            $qs[ $k ] = $v;
        }
    } else {
        $qs[ $args[0] ] = $args[1];
    }

    foreach ( $qs as $k => $v ) {
        if ( $v === false )
            unset( $qs[$k] );
    }

    $ret = build_query( $qs );
    $ret = trim( $ret, '?' );
    $ret = preg_replace( '#=(&|$)#', '$1', $ret );
    $ret = $protocol . $base . $ret . $frag;
    $ret = rtrim( $ret, '?' );
    return $ret;
}

/**
 * Removes an item or items from a query string.
 *
 * @since 1.5.0
 *
 * @param string|array $key   Query key or keys to remove.
 * @param bool|string  $query Optional. When false uses the current URL. Default false.
 * @return string New URL query string.
 */
function remove_query_arg( $key, $query = false ) {
    if ( is_array( $key ) ) { // removing multiple keys
        foreach ( $key as $k )
            $query = add_query_arg( $k, false, $query );
        return $query;
    }
    return add_query_arg( $key, false, $query );
}

/**
 * Returns an array of single-use query variable names that can be removed from a URL.
 *
 * @since 4.4.0
 *
 * @return array An array of parameters to remove from the URL.
 */
function wp_removable_query_args() {
    $removable_query_args = array(
        'activate',
        'activated',
        'approved',
        'deactivate',
        'deleted',
        'disabled',
        'enabled',
        'error',
        'hotkeys_highlight_first',
        'hotkeys_highlight_last',
        'locked',
        'message',
        'same',
        'saved',
        'settings-updated',
        'skipped',
        'spammed',
        'trashed',
        'unspammed',
        'untrashed',
        'update',
        'updated',
        'wp-post-new-reload',
    );

    /**
     * Filters the list of query variables to remove.
     *
     * @since 4.2.0
     *
     * @param array $removable_query_args An array of query variables to remove from a URL.
     */
    return apply_filters( 'removable_query_args', $removable_query_args );
}

/**
 * Walks the array while sanitizing the contents.
 *
 * @since 0.71
 *
 * @param array $array Array to walk while sanitizing contents.
 * @return array Sanitized $array.
 */
function add_magic_quotes( $array ) {
    foreach ( (array) $array as $k => $v ) {
        if ( is_array( $v ) ) {
            $array[$k] = add_magic_quotes( $v );
        } else {
            $array[$k] = addslashes( $v );
        }
    }
    return $array;
}

/**
 * HTTP request for URI to retrieve content.
 *
 * @since 1.5.1
 *
 * @see wp_safe_remote_get()
 *
 * @param string $uri URI/URL of web page to retrieve.
 * @return false|string HTTP content. False on failure.
 */
function wp_remote_fopen( $uri ) {
    $parsed_url = @parse_url( $uri );

    if ( !$parsed_url || !is_array( $parsed_url ) )
        return false;

    $options = array();
    $options['timeout'] = 10;

    $response = wp_safe_remote_get( $uri, $options );

    if ( is_wp_error( $response ) )
        return false;

    return wp_remote_retrieve_body( $response );
}

/**
 * Set up the WordPress query.
 *
 * @since 2.0.0
 *
 * @global WP       $wp_locale
 * @global WP_Query $wp_query
 * @global WP_Query $wp_the_query
 *
 * @param string|array $query_vars Default WP_Query arguments.
 */
function wp( $query_vars = '' ) {
    global $wp, $wp_query, $wp_the_query;
    $wp->main( $query_vars );

    if ( !isset($wp_the_query) )
        $wp_the_query = $wp_query;
}

/**
 * Retrieve the description for the HTTP status.
 *
 * @since 2.3.0
 *
 * @global array $wp_header_to_desc
 *
 * @param int $code HTTP status code.
 * @return string Empty string if not found, or description if found.
 */
function get_status_header_desc( $code ) {
    global $wp_header_to_desc;

    $code = absint( $code );

    if ( !isset( $wp_header_to_desc ) ) {
        $wp_header_to_desc = array(
            100 => 'Continue',
            101 => 'Switching Protocols',
            102 => 'Processing',

            200 => 'OK',
            201 => 'Created',
            202 => 'Accepted',
            203 => 'Non-Authoritative Information',
            204 => 'No Content',
            205 => 'Reset Content',
            206 => 'Partial Content',
            207 => 'Multi-Status',
            226 => 'IM Used',

            300 => 'Multiple Choices',
            301 => 'Moved Permanently',
            302 => 'Found',
            303 => 'See Other',
            304 => 'Not Modified',
            305 => 'Use Proxy',
            306 => 'Reserved',
            307 => 'Temporary Redirect',
            308 => 'Permanent Redirect',

            400 => 'Bad Request',
            401 => 'Unauthorized',
            402 => 'Payment Required',
            403 => 'Forbidden',
            404 => 'Not Found',
            405 => 'Method Not Allowed',
            406 => 'Not Acceptable',
            407 => 'Proxy Authentication Required',
            408 => 'Request Timeout',
            409 => 'Conflict',
            410 => 'Gone',
            411 => 'Length Required',
            412 => 'Precondition Failed',
            413 => 'Request Entity Too Large',
            414 => 'Request-URI Too Long',
            415 => 'Unsupported Media Type',
            416 => 'Requested Range Not Satisfiable',
            417 => 'Expectation Failed',
            418 => 'I\'m a teapot',
            421 => 'Misdirected Request',
            422 => 'Unprocessable Entity',
            423 => 'Locked',
            424 => 'Failed Dependency',
            426 => 'Upgrade Required',
            428 => 'Precondition Required',
            429 => 'Too Many Requests',
            431 => 'Request Header Fields Too Large',
            451 => 'Unavailable For Legal Reasons',

            500 => 'Internal Server Error',
            501 => 'Not Implemented',
            502 => 'Bad Gateway',
            503 => 'Service Unavailable',
            504 => 'Gateway Timeout',
            505 => 'HTTP Version Not Supported',
            506 => 'Variant Also Negotiates',
            507 => 'Insufficient Storage',
            510 => 'Not Extended',
            511 => 'Network Authentication Required',
        );
    }

    if ( isset( $wp_header_to_desc[$code] ) )
        return $wp_header_to_desc[$code];
    else
        return '';
}

/**
 * Set HTTP status header.
 *
 * @since 2.0.0
 * @since 4.4.0 Added the `$description` parameter.
 *
 * @see get_status_header_desc()
 *
 * @param int    $code        HTTP status code.
 * @param string $description Optional. A custom description for the HTTP status.
 */
function status_header( $code, $description = '' ) {
    if ( ! $description ) {
        $description = get_status_header_desc( $code );
    }

    if ( empty( $description ) ) {
        return;
    }

    $protocol = wp_get_server_protocol();
    $status_header = "$protocol $code $description";
    if ( function_exists( 'apply_filters' ) )

        /**
         * Filters an HTTP status header.
         *
         * @since 2.2.0
         *
         * @param string $status_header HTTP status header.
         * @param int    $code          HTTP status code.
         * @param string $description   Description for the status code.
         * @param string $protocol      Server protocol.
         */
        $status_header = apply_filters( 'status_header', $status_header, $code, $description, $protocol );

    @header( $status_header, true, $code );
}

/**
 * Get the header information to prevent caching.
 *
 * The several different headers cover the different ways cache prevention
 * is handled by different browsers
 *
 * @since 2.8.0
 *
 * @return array The associative array of header names and field values.
 */
function wp_get_nocache_headers() {
    $headers = array(
        'Expires' => 'Wed, 11 Jan 1984 05:00:00 GMT',
        'Cache-Control' => 'no-cache, must-revalidate, max-age=0',
    );

    if ( function_exists('apply_filters') ) {
        /**
         * Filters the cache-controlling headers.
         *
         * @since 2.8.0
         *
         * @see wp_get_nocache_headers()
         *
         * @param array $headers {
         *     Header names and field values.
         *
         *     @type string $Expires       Expires header.
         *     @type string $Cache-Control Cache-Control header.
         * }
         */
        $headers = (array) apply_filters( 'nocache_headers', $headers );
    }
    $headers['Last-Modified'] = false;
    return $headers;
}

/**
 * Set the headers to prevent caching for the different browsers.
 *
 * Different browsers support different nocache headers, so several
 * headers must be sent so that all of them get the point that no
 * caching should occur.
 *
 * @since 2.0.0
 *
 * @see wp_get_nocache_headers()
 */
function nocache_headers() {
    $headers = wp_get_nocache_headers();

    unset( $headers['Last-Modified'] );

    // In PHP 5.3+, make sure we are not sending a Last-Modified header.
    if ( function_exists( 'header_remove' ) ) {
        @header_remove( 'Last-Modified' );
    } else {
        // In PHP 5.2, send an empty Last-Modified header, but only as a
        // last resort to override a header already sent. #WP23021
        foreach ( headers_list() as $header ) {
            if ( 0 === stripos( $header, 'Last-Modified' ) ) {
                $headers['Last-Modified'] = '';
                break;
            }
        }
    }

    foreach ( $headers as $name => $field_value )
        @header("{$name}: {$field_value}");
}

/**
 * Set the headers for caching for 10 days with JavaScript content type.
 *
 * @since 2.1.0
 */
function cache_javascript_headers() {
    $expiresOffset = 10 * DAY_IN_SECONDS;

    header( "Content-Type: text/javascript; charset=" . get_bloginfo( 'charset' ) );
    header( "Vary: Accept-Encoding" ); // Handle proxies
    header( "Expires: " . gmdate( "D, d M Y H:i:s", time() + $expiresOffset ) . " GMT" );
}

/**
 * Retrieve the number of database queries during the WordPress execution.
 *
 * @since 2.0.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @return int Number of database queries.
 */
function get_num_queries() {
    global $wpdb;
    return $wpdb->num_queries;
}

/**
 * Whether input is yes or no.
 *
 * Must be 'y' to be true.
 *
 * @since 1.0.0
 *
 * @param string $yn Character string containing either 'y' (yes) or 'n' (no).
 * @return bool True if yes, false on anything else.
 */
function bool_from_yn( $yn ) {
    return ( strtolower( $yn ) == 'y' );
}

/**
 * Load the feed template from the use of an action hook.
 *
 * If the feed action does not have a hook, then the function will die with a
 * message telling the visitor that the feed is not valid.
 *
 * It is better to only have one hook for each feed.
 *
 * @since 2.1.0
 *
 * @global WP_Query $wp_query Used to tell if the use a comment feed.
 */
function do_feed() {
    global $wp_query;

    $feed = get_query_var( 'feed' );

    // Remove the pad, if present.
    $feed = preg_replace( '/^_+/', '', $feed );

    if ( $feed == '' || $feed == 'feed' )
        $feed = get_default_feed();

    if ( ! has_action( "do_feed_{$feed}" ) ) {
        wp_die( __( 'ERROR: This is not a valid feed template.' ), '', array( 'response' => 404 ) );
    }

    /**
     * Fires once the given feed is loaded.
     *
     * The dynamic portion of the hook name, `$feed`, refers to the feed template name.
     * Possible values include: 'rdf', 'rss', 'rss2', and 'atom'.
     *
     * @since 2.1.0
     * @since 4.4.0 The `$feed` parameter was added.
     *
     * @param bool   $is_comment_feed Whether the feed is a comment feed.
     * @param string $feed            The feed name.
     */
    do_action( "do_feed_{$feed}", $wp_query->is_comment_feed, $feed );
}

/**
 * Load the RDF RSS 0.91 Feed template.
 *
 * @since 2.1.0
 *
 * @see load_template()
 */
function do_feed_rdf() {
    load_template( ABSPATH . WPINC . '/feed-rdf.php' );
}

/**
 * Load the RSS 1.0 Feed Template.
 *
 * @since 2.1.0
 *
 * @see load_template()
 */
function do_feed_rss() {
    load_template( ABSPATH . WPINC . '/feed-rss.php' );
}

/**
 * Load either the RSS2 comment feed or the RSS2 posts feed.
 *
 * @since 2.1.0
 *
 * @see load_template()
 *
 * @param bool $for_comments True for the comment feed, false for normal feed.
 */
function do_feed_rss2( $for_comments ) {
    if ( $for_comments )
        load_template( ABSPATH . WPINC . '/feed-rss2-comments.php' );
    else
        load_template( ABSPATH . WPINC . '/feed-rss2.php' );
}

/**
 * Load either Atom comment feed or Atom posts feed.
 *
 * @since 2.1.0
 *
 * @see load_template()
 *
 * @param bool $for_comments True for the comment feed, false for normal feed.
 */
function do_feed_atom( $for_comments ) {
    if ($for_comments)
        load_template( ABSPATH . WPINC . '/feed-atom-comments.php');
    else
        load_template( ABSPATH . WPINC . '/feed-atom.php' );
}

/**
 * Display the robots.txt file content.
 *
 * The echo content should be with usage of the permalinks or for creating the
 * robots.txt file.
 *
 * @since 2.1.0
 */
function do_robots() {
    header( 'Content-Type: text/plain; charset=utf-8' );

    /**
     * Fires when displaying the robots.txt file.
     *
     * @since 2.1.0
     */
    do_action( 'do_robotstxt' );

    $output = "User-agent: *\n";
    $public = get_option( 'blog_public' );
    if ( '0' == $public ) {
        $output .= "Disallow: /\n";
    } else {
        $site_url = parse_url( site_url() );
        $path = ( !empty( $site_url['path'] ) ) ? $site_url['path'] : '';
        $output .= "Disallow: $path/wp-admin/\n";
        $output .= "Allow: $path/wp-admin/admin-ajax.php\n";
    }

    /**
     * Filters the robots.txt output.
     *
     * @since 3.0.0
     *
     * @param string $output Robots.txt output.
     * @param bool   $public Whether the site is considered "public".
     */
    echo apply_filters( 'robots_txt', $output, $public );
}

/**
 * Test whether WordPress is already installed.
 *
 * The cache will be checked first. If you have a cache plugin, which saves
 * the cache values, then this will work. If you use the default WordPress
 * cache, and the database goes away, then you might have problems.
 *
 * Checks for the 'siteurl' option for whether WordPress is installed.
 *
 * @since 2.1.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @return bool Whether the site is already installed.
 */
function is_blog_installed() {
    global $wpdb;

    /*
     * Check cache first. If options table goes away and we have true
     * cached, oh well.
     */
    if ( wp_cache_get( 'is_blog_installed' ) )
        return true;

    $suppress = $wpdb->suppress_errors();
    if ( ! wp_installing() ) {
        $alloptions = wp_load_alloptions();
    }
    // If siteurl is not set to autoload, check it specifically
    if ( !isset( $alloptions['siteurl'] ) )
        $installed = $wpdb->get_var( "SELECT option_value FROM $wpdb->options WHERE option_name = 'siteurl'" );
    else
        $installed = $alloptions['siteurl'];
    $wpdb->suppress_errors( $suppress );

    $installed = !empty( $installed );
    wp_cache_set( 'is_blog_installed', $installed );

    if ( $installed )
        return true;

    // If visiting repair.php, return true and let it take over.
    if ( defined( 'WP_REPAIRING' ) )
        return true;

    $suppress = $wpdb->suppress_errors();

    /*
     * Loop over the WP tables. If none exist, then scratch install is allowed.
     * If one or more exist, suggest table repair since we got here because the
     * options table could not be accessed.
     */
    $wp_tables = $wpdb->tables();
    foreach ( $wp_tables as $table ) {
        // The existence of custom user tables shouldn't suggest an insane state or prevent a clean install.
        if ( defined( 'CUSTOM_USER_TABLE' ) && CUSTOM_USER_TABLE == $table )
            continue;
        if ( defined( 'CUSTOM_USER_META_TABLE' ) && CUSTOM_USER_META_TABLE == $table )
            continue;

        if ( ! $wpdb->get_results( "DESCRIBE $table;" ) )
            continue;

        // One or more tables exist. We are insane.

        wp_load_translations_early();

        // Die with a DB error.
        $wpdb->error = sprintf(
        /* translators: %s: database repair URL */
            __( 'One or more database tables are unavailable. The database may need to be <a href="%s">repaired</a>.' ),
            'maint/repair.php?referrer=is_blog_installed'
        );

        dead_db();
    }

    $wpdb->suppress_errors( $suppress );

    wp_cache_set( 'is_blog_installed', false );

    return false;
}

/**
 * Retrieve URL with nonce added to URL query.
 *
 * @since 2.0.4
 *
 * @param string     $actionurl URL to add nonce action.
 * @param int|string $action    Optional. Nonce action name. Default -1.
 * @param string     $name      Optional. Nonce name. Default '_wpnonce'.
 * @return string Escaped URL with nonce action added.
 */
function wp_nonce_url( $actionurl, $action = -1, $name = '_wpnonce' ) {
    $actionurl = str_replace( '&amp;', '&', $actionurl );
    return esc_html( add_query_arg( $name, wp_create_nonce( $action ), $actionurl ) );
}

/**
 * Retrieve or display nonce hidden field for forms.
 *
 * The nonce field is used to validate that the contents of the form came from
 * the location on the current site and not somewhere else. The nonce does not
 * offer absolute protection, but should protect against most cases. It is very
 * important to use nonce field in forms.
 *
 * The $action and $name are optional, but if you want to have better security,
 * it is strongly suggested to set those two parameters. It is easier to just
 * call the function without any parameters, because validation of the nonce
 * doesn't require any parameters, but since crackers know what the default is
 * it won't be difficult for them to find a way around your nonce and cause
 * damage.
 *
 * The input name will be whatever $name value you gave. The input value will be
 * the nonce creation value.
 *
 * @since 2.0.4
 *
 * @param int|string $action  Optional. Action name. Default -1.
 * @param string     $name    Optional. Nonce name. Default '_wpnonce'.
 * @param bool       $referer Optional. Whether to set the referer field for validation. Default true.
 * @param bool       $echo    Optional. Whether to display or return hidden form field. Default true.
 * @return string Nonce field HTML markup.
 */
function wp_nonce_field( $action = -1, $name = "_wpnonce", $referer = true , $echo = true ) {
    $name = esc_attr( $name );
    $nonce_field = '<input type="hidden" id="' . $name . '" name="' . $name . '" value="' . wp_create_nonce( $action ) . '" />';

    if ( $referer )
        $nonce_field .= wp_referer_field( false );

    if ( $echo )
        echo $nonce_field;

    return $nonce_field;
}

/**
 * Retrieve or display referer hidden field for forms.
 *
 * The referer link is the current Request URI from the server super global. The
 * input name is '_wp_http_referer', in case you wanted to check manually.
 *
 * @since 2.0.4
 *
 * @param bool $echo Optional. Whether to echo or return the referer field. Default true.
 * @return string Referer field HTML markup.
 */
function wp_referer_field( $echo = true ) {
    $referer_field = '<input type="hidden" name="_wp_http_referer" value="'. esc_attr( wp_unslash( $_SERVER['REQUEST_URI'] ) ) . '" />';

    if ( $echo )
        echo $referer_field;
    return $referer_field;
}

/**
 * Retrieve or display original referer hidden field for forms.
 *
 * The input name is '_wp_original_http_referer' and will be either the same
 * value of wp_referer_field(), if that was posted already or it will be the
 * current page, if it doesn't exist.
 *
 * @since 2.0.4
 *
 * @param bool   $echo         Optional. Whether to echo the original http referer. Default true.
 * @param string $jump_back_to Optional. Can be 'previous' or page you want to jump back to.
 *                             Default 'current'.
 * @return string Original referer field.
 */
function wp_original_referer_field( $echo = true, $jump_back_to = 'current' ) {
    if ( ! $ref = wp_get_original_referer() ) {
        $ref = 'previous' == $jump_back_to ? wp_get_referer() : wp_unslash( $_SERVER['REQUEST_URI'] );
    }
    $orig_referer_field = '<input type="hidden" name="_wp_original_http_referer" value="' . esc_attr( $ref ) . '" />';
    if ( $echo )
        echo $orig_referer_field;
    return $orig_referer_field;
}

/**
 * Retrieve referer from '_wp_http_referer' or HTTP referer.
 *
 * If it's the same as the current request URL, will return false.
 *
 * @since 2.0.4
 *
 * @return false|string False on failure. Referer URL on success.
 */
function wp_get_referer() {
    if ( ! function_exists( 'wp_validate_redirect' ) ) {
        return false;
    }

    $ref = wp_get_raw_referer();

    if ( $ref && $ref !== wp_unslash( $_SERVER['REQUEST_URI'] ) && $ref !== home_url() . wp_unslash( $_SERVER['REQUEST_URI'] ) ) {
        return wp_validate_redirect( $ref, false );
    }

    return false;
}

/**
 * Retrieves unvalidated referer from '_wp_http_referer' or HTTP referer.
 *
 * Do not use for redirects, use wp_get_referer() instead.
 *
 * @since 4.5.0
 *
 * @return string|false Referer URL on success, false on failure.
 */
function wp_get_raw_referer() {
    if ( ! empty( $_REQUEST['_wp_http_referer'] ) ) {
        return wp_unslash( $_REQUEST['_wp_http_referer'] );
    } else if ( ! empty( $_SERVER['HTTP_REFERER'] ) ) {
        return wp_unslash( $_SERVER['HTTP_REFERER'] );
    }

    return false;
}

/**
 * Retrieve original referer that was posted, if it exists.
 *
 * @since 2.0.4
 *
 * @return string|false False if no original referer or original referer if set.
 */
function wp_get_original_referer() {
    if ( ! empty( $_REQUEST['_wp_original_http_referer'] ) && function_exists( 'wp_validate_redirect' ) )
        return wp_validate_redirect( wp_unslash( $_REQUEST['_wp_original_http_referer'] ), false );
    return false;
}

/**
 * Recursive directory creation based on full path.
 *
 * Will attempt to set permissions on folders.
 *
 * @since 2.0.1
 *
 * @param string $target Full path to attempt to create.
 * @return bool Whether the path was created. True if path already exists.
 */
function wp_mkdir_p( $target ) {
    $wrapper = null;

    // Strip the protocol.
    if ( wp_is_stream( $target ) ) {
        list( $wrapper, $target ) = explode( '://', $target, 2 );
    }

    // From php.net/mkdir user contributed notes.
    $target = str_replace( '//', '/', $target );

    // Put the wrapper back on the target.
    if ( $wrapper !== null ) {
        $target = $wrapper . '://' . $target;
    }

    /*
     * Safe mode fails with a trailing slash under certain PHP versions.
     * Use rtrim() instead of untrailingslashit to avoid formatting.php dependency.
     */
    $target = rtrim($target, '/');
    if ( empty($target) )
        $target = '/';

    if ( file_exists( $target ) )
        return @is_dir( $target );

    // We need to find the permissions of the parent folder that exists and inherit that.
    $target_parent = dirname( $target );
    while ( '.' != $target_parent && ! is_dir( $target_parent ) ) {
        $target_parent = dirname( $target_parent );
    }

    // Get the permission bits.
    if ( $stat = @stat( $target_parent ) ) {
        $dir_perms = $stat['mode'] & 0007777;
    } else {
        $dir_perms = 0777;
    }

    if ( @mkdir( $target, $dir_perms, true ) ) {

        /*
         * If a umask is set that modifies $dir_perms, we'll have to re-set
         * the $dir_perms correctly with chmod()
         */
        if ( $dir_perms != ( $dir_perms & ~umask() ) ) {
            $folder_parts = explode( '/', substr( $target, strlen( $target_parent ) + 1 ) );
            for ( $i = 1, $c = count( $folder_parts ); $i <= $c; $i++ ) {
                @chmod( $target_parent . '/' . implode( '/', array_slice( $folder_parts, 0, $i ) ), $dir_perms );
            }
        }

        return true;
    }

    return false;
}

/**
 * Test if a give filesystem path is absolute.
 *
 * For example, '/foo/bar', or 'c:\windows'.
 *
 * @since 2.5.0
 *
 * @param string $path File path.
 * @return bool True if path is absolute, false is not absolute.
 */
function path_is_absolute( $path ) {
    /*
     * This is definitive if true but fails if $path does not exist or contains
     * a symbolic link.
     */
    if ( realpath($path) == $path )
        return true;

    if ( strlen($path) == 0 || $path[0] == '.' )
        return false;

    // Windows allows absolute paths like this.
    if ( preg_match('#^[a-zA-Z]:\\\\#', $path) )
        return true;

    // A path starting with / or \ is absolute; anything else is relative.
    return ( $path[0] == '/' || $path[0] == '\\' );
}

/**
 * Join two filesystem paths together.
 *
 * For example, 'give me $path relative to $base'. If the $path is absolute,
 * then it the full path is returned.
 *
 * @since 2.5.0
 *
 * @param string $base Base path.
 * @param string $path Path relative to $base.
 * @return string The path with the base or absolute path.
 */
function path_join( $base, $path ) {
    if ( path_is_absolute($path) )
        return $path;

    return rtrim($base, '/') . '/' . ltrim($path, '/');
}

/**
 * Normalize a filesystem path.
 *
 * On windows systems, replaces backslashes with forward slashes
 * and forces upper-case drive letters.
 * Allows for two leading slashes for Windows network shares, but
 * ensures that all other duplicate slashes are reduced to a single.
 *
 * @since 3.9.0
 * @since 4.4.0 Ensures upper-case drive letters on Windows systems.
 * @since 4.5.0 Allows for Windows network shares.
 *
 * @param string $path Path to normalize.
 * @return string Normalized path.
 */
function wp_normalize_path( $path ) {
    $path = str_replace( '\\', '/', $path );
    $path = preg_replace( '|(?<=.)/+|', '/', $path );
    if ( ':' === substr( $path, 1, 1 ) ) {
        $path = ucfirst( $path );
    }
    return $path;
}

/**
 * Determine a writable directory for temporary files.
 *
 * Function's preference is the return value of sys_get_temp_dir(),
 * followed by your PHP temporary upload directory, followed by WP_CONTENT_DIR,
 * before finally defaulting to /tmp/
 *
 * In the event that this function does not find a writable location,
 * It may be overridden by the WP_TEMP_DIR constant in your wp-config.php file.
 *
 * @since 2.5.0
 *
 * @staticvar string $temp
 *
 * @return string Writable temporary directory.
 */
function get_temp_dir() {
    static $temp = '';
    if ( defined('WP_TEMP_DIR') )
        return trailingslashit(WP_TEMP_DIR);

    if ( $temp )
        return trailingslashit( $temp );

    if ( function_exists('sys_get_temp_dir') ) {
        $temp = sys_get_temp_dir();
        if ( @is_dir( $temp ) && wp_is_writable( $temp ) )
            return trailingslashit( $temp );
    }

    $temp = ini_get('upload_tmp_dir');
    if ( @is_dir( $temp ) && wp_is_writable( $temp ) )
        return trailingslashit( $temp );

    $temp = WP_CONTENT_DIR . '/';
    if ( is_dir( $temp ) && wp_is_writable( $temp ) )
        return $temp;

    return '/tmp/';
}

/**
 * Determine if a directory is writable.
 *
 * This function is used to work around certain ACL issues in PHP primarily
 * affecting Windows Servers.
 *
 * @since 3.6.0
 *
 * @see win_is_writable()
 *
 * @param string $path Path to check for write-ability.
 * @return bool Whether the path is writable.
 */
function wp_is_writable( $path ) {
    if ( 'WIN' === strtoupper( substr( PHP_OS, 0, 3 ) ) )
        return win_is_writable( $path );
    else
        return @is_writable( $path );
}

/**
 * Workaround for Windows bug in is_writable() function
 *
 * PHP has issues with Windows ACL's for determine if a
 * directory is writable or not, this works around them by
 * checking the ability to open files rather than relying
 * upon PHP to interprate the OS ACL.
 *
 * @since 2.8.0
 *
 * @see https://bugs.php.net/bug.php?id=27609
 * @see https://bugs.php.net/bug.php?id=30931
 *
 * @param string $path Windows path to check for write-ability.
 * @return bool Whether the path is writable.
 */
function win_is_writable( $path ) {

    if ( $path[strlen( $path ) - 1] == '/' ) { // if it looks like a directory, check a random file within the directory
        return win_is_writable( $path . uniqid( mt_rand() ) . '.tmp');
    } elseif ( is_dir( $path ) ) { // If it's a directory (and not a file) check a random file within the directory
        return win_is_writable( $path . '/' . uniqid( mt_rand() ) . '.tmp' );
    }
    // check tmp file for read/write capabilities
    $should_delete_tmp_file = !file_exists( $path );
    $f = @fopen( $path, 'a' );
    if ( $f === false )
        return false;
    fclose( $f );
    if ( $should_delete_tmp_file )
        unlink( $path );
    return true;
}

/**
 * Retrieves uploads directory information.
 *
 * Same as wp_upload_dir() but "light weight" as it doesn't attempt to create the uploads directory.
 * Intended for use in themes, when only 'basedir' and 'baseurl' are needed, generally in all cases
 * when not uploading files.
 *
 * @since 4.5.0
 *
 * @see wp_upload_dir()
 *
 * @return array See wp_upload_dir() for description.
 */
function wp_get_upload_dir() {
    return wp_upload_dir( null, false );
}

/**
 * Get an array containing the current upload directory's path and url.
 *
 * Checks the 'upload_path' option, which should be from the web root folder,
 * and if it isn't empty it will be used. If it is empty, then the path will be
 * 'WP_CONTENT_DIR/uploads'. If the 'UPLOADS' constant is defined, then it will
 * override the 'upload_path' option and 'WP_CONTENT_DIR/uploads' path.
 *
 * The upload URL path is set either by the 'upload_url_path' option or by using
 * the 'WP_CONTENT_URL' constant and appending '/uploads' to the path.
 *
 * If the 'uploads_use_yearmonth_folders' is set to true (checkbox if checked in
 * the administration settings panel), then the time will be used. The format
 * will be year first and then month.
 *
 * If the path couldn't be created, then an error will be returned with the key
 * 'error' containing the error message. The error suggests that the parent
 * directory is not writable by the server.
 *
 * On success, the returned array will have many indices:
 * 'path' - base directory and sub directory or full path to upload directory.
 * 'url' - base url and sub directory or absolute URL to upload directory.
 * 'subdir' - sub directory if uploads use year/month folders option is on.
 * 'basedir' - path without subdir.
 * 'baseurl' - URL path without subdir.
 * 'error' - false or error message.
 *
 * @since 2.0.0
 * @uses _wp_upload_dir()
 *
 * @param string $time Optional. Time formatted in 'yyyy/mm'. Default null.
 * @param bool   $create_dir Optional. Whether to check and create the uploads directory.
 *                           Default true for backward compatibility.
 * @param bool   $refresh_cache Optional. Whether to refresh the cache. Default false.
 * @return array See above for description.
 */
function wp_upload_dir( $time = null, $create_dir = true, $refresh_cache = false ) {
    static $cache = array(), $tested_paths = array();

    $key = sprintf( '%d-%s', get_current_blog_id(), (string) $time );

    if ( $refresh_cache || empty( $cache[ $key ] ) ) {
        $cache[ $key ] = _wp_upload_dir( $time );
    }

    /**
     * Filters the uploads directory data.
     *
     * @since 2.0.0
     *
     * @param array $uploads Array of upload directory data with keys of 'path',
     *                       'url', 'subdir, 'basedir', and 'error'.
     */
    $uploads = apply_filters( 'upload_dir', $cache[ $key ] );

    if ( $create_dir ) {
        $path = $uploads['path'];

        if ( array_key_exists( $path, $tested_paths ) ) {
            $uploads['error'] = $tested_paths[ $path ];
        } else {
            if ( ! wp_mkdir_p( $path ) ) {
                if ( 0 === strpos( $uploads['basedir'], ABSPATH ) ) {
                    $error_path = str_replace( ABSPATH, '', $uploads['basedir'] ) . $uploads['subdir'];
                } else {
                    $error_path = basename( $uploads['basedir'] ) . $uploads['subdir'];
                }

                $uploads['error'] = sprintf(
                /* translators: %s: directory path */
                    __( 'Unable to create directory %s. Is its parent directory writable by the server?' ),
                    esc_html( $error_path )
                );
            }

            $tested_paths[ $path ] = $uploads['error'];
        }
    }

    return $uploads;
}

/**
 * A non-filtered, non-cached version of wp_upload_dir() that doesn't check the path.
 *
 * @access private
 *
 * @param string $time Optional. Time formatted in 'yyyy/mm'. Default null.
 * @return array See wp_upload_dir()
 */
function _wp_upload_dir( $time = null ) {
    $siteurl = get_option( 'siteurl' );
    $upload_path = trim( get_option( 'upload_path' ) );

    if ( empty( $upload_path ) || 'wp-content/uploads' == $upload_path ) {
        $dir = WP_CONTENT_DIR . '/uploads';
    } elseif ( 0 !== strpos( $upload_path, ABSPATH ) ) {
        // $dir is absolute, $upload_path is (maybe) relative to ABSPATH
        $dir = path_join( ABSPATH, $upload_path );
    } else {
        $dir = $upload_path;
    }

    if ( !$url = get_option( 'upload_url_path' ) ) {
        if ( empty($upload_path) || ( 'wp-content/uploads' == $upload_path ) || ( $upload_path == $dir ) )
            $url = WP_CONTENT_URL . '/uploads';
        else
            $url = trailingslashit( $siteurl ) . $upload_path;
    }

    /*
     * Honor the value of UPLOADS. This happens as long as ms-files rewriting is disabled.
     * We also sometimes obey UPLOADS when rewriting is enabled -- see the next block.
     */
    if ( defined( 'UPLOADS' ) && ! ( is_multisite() && get_site_option( 'ms_files_rewriting' ) ) ) {
        $dir = ABSPATH . UPLOADS;
        $url = trailingslashit( $siteurl ) . UPLOADS;
    }

    // If multisite (and if not the main site in a post-MU network)
    if ( is_multisite() && ! ( is_main_network() && is_main_site() && defined( 'MULTISITE' ) ) ) {

        if ( ! get_site_option( 'ms_files_rewriting' ) ) {
            /*
             * If ms-files rewriting is disabled (networks created post-3.5), it is fairly
             * straightforward: Append sites/%d if we're not on the main site (for post-MU
             * networks). (The extra directory prevents a four-digit ID from conflicting with
             * a year-based directory for the main site. But if a MU-era network has disabled
             * ms-files rewriting manually, they don't need the extra directory, as they never
             * had wp-content/uploads for the main site.)
             */

            if ( defined( 'MULTISITE' ) )
                $ms_dir = '/sites/' . get_current_blog_id();
            else
                $ms_dir = '/' . get_current_blog_id();

            $dir .= $ms_dir;
            $url .= $ms_dir;

        } elseif ( defined( 'UPLOADS' ) && ! ms_is_switched() ) {
            /*
             * Handle the old-form ms-files.php rewriting if the network still has that enabled.
             * When ms-files rewriting is enabled, then we only listen to UPLOADS when:
             * 1) We are not on the main site in a post-MU network, as wp-content/uploads is used
             *    there, and
             * 2) We are not switched, as ms_upload_constants() hardcodes these constants to reflect
             *    the original blog ID.
             *
             * Rather than UPLOADS, we actually use BLOGUPLOADDIR if it is set, as it is absolute.
             * (And it will be set, see ms_upload_constants().) Otherwise, UPLOADS can be used, as
             * as it is relative to ABSPATH. For the final piece: when UPLOADS is used with ms-files
             * rewriting in multisite, the resulting URL is /files. (#WP22702 for background.)
             */

            if ( defined( 'BLOGUPLOADDIR' ) )
                $dir = untrailingslashit( BLOGUPLOADDIR );
            else
                $dir = ABSPATH . UPLOADS;
            $url = trailingslashit( $siteurl ) . 'files';
        }
    }

    $basedir = $dir;
    $baseurl = $url;

    $subdir = '';
    if ( get_option( 'uploads_use_yearmonth_folders' ) ) {
        // Generate the yearly and monthly dirs
        if ( !$time )
            $time = current_time( 'mysql' );
        $y = substr( $time, 0, 4 );
        $m = substr( $time, 5, 2 );
        $subdir = "/$y/$m";
    }

    $dir .= $subdir;
    $url .= $subdir;

    return array(
        'path'    => $dir,
        'url'     => $url,
        'subdir'  => $subdir,
        'basedir' => $basedir,
        'baseurl' => $baseurl,
        'error'   => false,
    );
}

/**
 * Get a filename that is sanitized and unique for the given directory.
 *
 * If the filename is not unique, then a number will be added to the filename
 * before the extension, and will continue adding numbers until the filename is
 * unique.
 *
 * The callback is passed three parameters, the first one is the directory, the
 * second is the filename, and the third is the extension.
 *
 * @since 2.5.0
 *
 * @param string   $dir                      Directory.
 * @param string   $filename                 File name.
 * @param callable $unique_filename_callback Callback. Default null.
 * @return string New filename, if given wasn't unique.
 */
function wp_unique_filename( $dir, $filename, $unique_filename_callback = null ) {
    // Sanitize the file name before we begin processing.
    $filename = sanitize_file_name($filename);

    // Separate the filename into a name and extension.
    $ext = pathinfo( $filename, PATHINFO_EXTENSION );
    $name = pathinfo( $filename, PATHINFO_BASENAME );
    if ( $ext ) {
        $ext = '.' . $ext;
    }

    // Edge case: if file is named '.ext', treat as an empty name.
    if ( $name === $ext ) {
        $name = '';
    }

    /*
     * Increment the file number until we have a unique file to save in $dir.
     * Use callback if supplied.
     */
    if ( $unique_filename_callback && is_callable( $unique_filename_callback ) ) {
        $filename = call_user_func( $unique_filename_callback, $dir, $name, $ext );
    } else {
        $number = '';

        // Change '.ext' to lower case.
        if ( $ext && strtolower($ext) != $ext ) {
            $ext2 = strtolower($ext);
            $filename2 = preg_replace( '|' . preg_quote($ext) . '$|', $ext2, $filename );

            // Check for both lower and upper case extension or image sub-sizes may be overwritten.
            while ( file_exists($dir . "/$filename") || file_exists($dir . "/$filename2") ) {
                $new_number = (int) $number + 1;
                $filename = str_replace( array( "-$number$ext", "$number$ext" ), "-$new_number$ext", $filename );
                $filename2 = str_replace( array( "-$number$ext2", "$number$ext2" ), "-$new_number$ext2", $filename2 );
                $number = $new_number;
            }

            /**
             * Filters the result when generating a unique file name.
             *
             * @since 4.5.0
             *
             * @param string        $filename                 Unique file name.
             * @param string        $ext                      File extension, eg. ".png".
             * @param string        $dir                      Directory path.
             * @param callable|null $unique_filename_callback Callback function that generates the unique file name.
             */
            return apply_filters( 'wp_unique_filename', $filename2, $ext, $dir, $unique_filename_callback );
        }

        while ( file_exists( $dir . "/$filename" ) ) {
            $new_number = (int) $number + 1;
            if ( '' == "$number$ext" ) {
                $filename = "$filename-" . $new_number;
            } else {
                $filename = str_replace( array( "-$number$ext", "$number$ext" ), "-" . $new_number . $ext, $filename );
            }
            $number = $new_number;
        }
    }

    /** This filter is documented in wp-includes/functions.php */
    return apply_filters( 'wp_unique_filename', $filename, $ext, $dir, $unique_filename_callback );
}

/**
 * Create a file in the upload folder with given content.
 *
 * If there is an error, then the key 'error' will exist with the error message.
 * If success, then the key 'file' will have the unique file path, the 'url' key
 * will have the link to the new file. and the 'error' key will be set to false.
 *
 * This function will not move an uploaded file to the upload folder. It will
 * create a new file with the content in $bits parameter. If you move the upload
 * file, read the content of the uploaded file, and then you can give the
 * filename and content to this function, which will add it to the upload
 * folder.
 *
 * The permissions will be set on the new file automatically by this function.
 *
 * @since 2.0.0
 *
 * @param string       $name       Filename.
 * @param null|string  $deprecated Never used. Set to null.
 * @param mixed        $bits       File content
 * @param string       $time       Optional. Time formatted in 'yyyy/mm'. Default null.
 * @return array
 */
function wp_upload_bits( $name, $deprecated, $bits, $time = null ) {
    if ( !empty( $deprecated ) )
        _deprecated_argument( __FUNCTION__, '2.0.0' );

    if ( empty( $name ) )
        return array( 'error' => __( 'Empty filename' ) );

    $wp_filetype = wp_check_filetype( $name );
    if ( ! $wp_filetype['ext'] && ! current_user_can( 'unfiltered_upload' ) )
        return array( 'error' => __( 'Invalid file type' ) );

    $upload = wp_upload_dir( $time );

    if ( $upload['error'] !== false )
        return $upload;

    /**
     * Filters whether to treat the upload bits as an error.
     *
     * Passing a non-array to the filter will effectively short-circuit preparing
     * the upload bits, returning that value instead.
     *
     * @since 3.0.0
     *
     * @param mixed $upload_bits_error An array of upload bits data, or a non-array error to return.
     */
    $upload_bits_error = apply_filters( 'wp_upload_bits', array( 'name' => $name, 'bits' => $bits, 'time' => $time ) );
    if ( !is_array( $upload_bits_error ) ) {
        $upload[ 'error' ] = $upload_bits_error;
        return $upload;
    }

    $filename = wp_unique_filename( $upload['path'], $name );

    $new_file = $upload['path'] . "/$filename";
    if ( ! wp_mkdir_p( dirname( $new_file ) ) ) {
        if ( 0 === strpos( $upload['basedir'], ABSPATH ) )
            $error_path = str_replace( ABSPATH, '', $upload['basedir'] ) . $upload['subdir'];
        else
            $error_path = basename( $upload['basedir'] ) . $upload['subdir'];

        $message = sprintf(
        /* translators: %s: directory path */
            __( 'Unable to create directory %s. Is its parent directory writable by the server?' ),
            $error_path
        );
        return array( 'error' => $message );
    }

    $ifp = @ fopen( $new_file, 'wb' );
    if ( ! $ifp )
        return array( 'error' => sprintf( __( 'Could not write file %s' ), $new_file ) );

    @fwrite( $ifp, $bits );
    fclose( $ifp );
    clearstatcache();

    // Set correct file permissions
    $stat = @ stat( dirname( $new_file ) );
    $perms = $stat['mode'] & 0007777;
    $perms = $perms & 0000666;
    @ chmod( $new_file, $perms );
    clearstatcache();

    // Compute the URL
    $url = $upload['url'] . "/$filename";

    /** This filter is documented in wp-admin/includes/file.php */
    return apply_filters( 'wp_handle_upload', array( 'file' => $new_file, 'url' => $url, 'type' => $wp_filetype['type'], 'error' => false ), 'sideload' );
}

/**
 * Retrieve the file type based on the extension name.
 *
 * @since 2.5.0
 *
 * @param string $ext The extension to search.
 * @return string|void The file type, example: audio, video, document, spreadsheet, etc.
 */
function wp_ext2type( $ext ) {
    $ext = strtolower( $ext );

    $ext2type = wp_get_ext_types();
    foreach ( $ext2type as $type => $exts )
        if ( in_array( $ext, $exts ) )
            return $type;
}

/**
 * Retrieve the file type from the file name.
 *
 * You can optionally define the mime array, if needed.
 *
 * @since 2.0.4
 *
 * @param string $filename File name or path.
 * @param array  $mimes    Optional. Key is the file extension with value as the mime type.
 * @return array Values with extension first and mime type.
 */
function wp_check_filetype( $filename, $mimes = null ) {
    if ( empty($mimes) )
        $mimes = get_allowed_mime_types();
    $type = false;
    $ext = false;

    foreach ( $mimes as $ext_preg => $mime_match ) {
        $ext_preg = '!\.(' . $ext_preg . ')$!i';
        if ( preg_match( $ext_preg, $filename, $ext_matches ) ) {
            $type = $mime_match;
            $ext = $ext_matches[1];
            break;
        }
    }

    return compact( 'ext', 'type' );
}

/**
 * Attempt to determine the real file type of a file.
 *
 * If unable to, the file name extension will be used to determine type.
 *
 * If it's determined that the extension does not match the file's real type,
 * then the "proper_filename" value will be set with a proper filename and extension.
 *
 * Currently this function only supports renaming images validated via wp_get_image_mime().
 *
 * @since 3.0.0
 *
 * @param string $file     Full path to the file.
 * @param string $filename The name of the file (may differ from $file due to $file being
 *                         in a tmp directory).
 * @param array   $mimes   Optional. Key is the file extension with value as the mime type.
 * @return array Values for the extension, MIME, and either a corrected filename or false
 *               if original $filename is valid.
 */
function wp_check_filetype_and_ext( $file, $filename, $mimes = null ) {
    $proper_filename = false;

    // Do basic extension validation and MIME mapping
    $wp_filetype = wp_check_filetype( $filename, $mimes );
    $ext = $wp_filetype['ext'];
    $type = $wp_filetype['type'];

    // We can't do any further validation without a file to work with
    if ( ! file_exists( $file ) ) {
        return compact( 'ext', 'type', 'proper_filename' );
    }

    $real_mime = false;

    // Validate image types.
    if ( $type && 0 === strpos( $type, 'image/' ) ) {

        // Attempt to figure out what type of image it actually is
        $real_mime = wp_get_image_mime( $file );

        if ( $real_mime && $real_mime != $type ) {
            /**
             * Filters the list mapping image mime types to their respective extensions.
             *
             * @since 3.0.0
             *
             * @param  array $mime_to_ext Array of image mime types and their matching extensions.
             */
            $mime_to_ext = apply_filters( 'getimagesize_mimes_to_exts', array(
                'image/jpeg' => 'jpg',
                'image/png'  => 'png',
                'image/gif'  => 'gif',
                'image/bmp'  => 'bmp',
                'image/tiff' => 'tif',
            ) );

            // Replace whatever is after the last period in the filename with the correct extension
            if ( ! empty( $mime_to_ext[ $real_mime ] ) ) {
                $filename_parts = explode( '.', $filename );
                array_pop( $filename_parts );
                $filename_parts[] = $mime_to_ext[ $real_mime ];
                $new_filename = implode( '.', $filename_parts );

                if ( $new_filename != $filename ) {
                    $proper_filename = $new_filename; // Mark that it changed
                }
                // Redefine the extension / MIME
                $wp_filetype = wp_check_filetype( $new_filename, $mimes );
                $ext = $wp_filetype['ext'];
                $type = $wp_filetype['type'];
            } else {
                // Reset $real_mime and try validating again.
                $real_mime = false;
            }
        }
    }

    // Validate files that didn't get validated during previous checks.
    if ( $type && ! $real_mime && extension_loaded( 'fileinfo' ) ) {
        $finfo = finfo_open( FILEINFO_MIME_TYPE );
        $real_mime = finfo_file( $finfo, $file );
        finfo_close( $finfo );

        /*
         * If $real_mime doesn't match what we're expecting, we need to do some extra
         * vetting of application mime types to make sure this type of file is allowed.
         * Other mime types are assumed to be safe, but should be considered unverified.
         */
        if ( $real_mime && ( $real_mime !== $type ) && ( 0 === strpos( $real_mime, 'application' ) ) ) {
            $allowed = get_allowed_mime_types();

            if ( ! in_array( $real_mime, $allowed ) ) {
                $type = $ext = false;
            }
        }
    }

    /**
     * Filters the "real" file type of the given file.
     *
     * @since 3.0.0
     *
     * @param array  $wp_check_filetype_and_ext File data array containing 'ext', 'type', and
     *                                          'proper_filename' keys.
     * @param string $file                      Full path to the file.
     * @param string $filename                  The name of the file (may differ from $file due to
     *                                          $file being in a tmp directory).
     * @param array  $mimes                     Key is the file extension with value as the mime type.
     */
    return apply_filters( 'wp_check_filetype_and_ext', compact( 'ext', 'type', 'proper_filename' ), $file, $filename, $mimes );
}

/**
 * Returns the real mime type of an image file.
 *
 * This depends on exif_imagetype() or getimagesize() to determine real mime types.
 *
 * @since 4.7.1
 *
 * @param string $file Full path to the file.
 * @return string|false The actual mime type or false if the type cannot be determined.
 */
function wp_get_image_mime( $file ) {
    /*
     * Use exif_imagetype() to check the mimetype if available or fall back to
     * getimagesize() if exif isn't avaialbe. If either function throws an Exception
     * we assume the file could not be validated.
     */
    try {
        if ( is_callable( 'exif_imagetype' ) ) {
            $mime = image_type_to_mime_type( exif_imagetype( $file ) );
        } elseif ( function_exists( 'getimagesize' ) ) {
            $imagesize = getimagesize( $file );
            $mime = ( isset( $imagesize['mime'] ) ) ? $imagesize['mime'] : false;
        } else {
            $mime = false;
        }
    } catch ( Exception $e ) {
        $mime = false;
    }

    return $mime;
}

/**
 * Retrieve list of mime types and file extensions.
 *
 * @since 3.5.0
 * @since 4.2.0 Support was added for GIMP (xcf) files.
 *
 * @return array Array of mime types keyed by the file extension regex corresponding to those types.
 */
function wp_get_mime_types() {
    /**
     * Filters the list of mime types and file extensions.
     *
     * This filter should be used to add, not remove, mime types. To remove
     * mime types, use the {@see 'upload_mimes'} filter.
     *
     * @since 3.5.0
     *
     * @param array $wp_get_mime_types Mime types keyed by the file extension regex
     *                                 corresponding to those types.
     */
    return apply_filters( 'mime_types', array(
        // Image formats.
        'jpg|jpeg|jpe' => 'image/jpeg',
        'gif' => 'image/gif',
        'png' => 'image/png',
        'bmp' => 'image/bmp',
        'tiff|tif' => 'image/tiff',
        'ico' => 'image/x-icon',
        // Video formats.
        'asf|asx' => 'video/x-ms-asf',
        'wmv' => 'video/x-ms-wmv',
        'wmx' => 'video/x-ms-wmx',
        'wm' => 'video/x-ms-wm',
        'avi' => 'video/avi',
        'divx' => 'video/divx',
        'flv' => 'video/x-flv',
        'mov|qt' => 'video/quicktime',
        'mpeg|mpg|mpe' => 'video/mpeg',
        'mp4|m4v' => 'video/mp4',
        'ogv' => 'video/ogg',
        'webm' => 'video/webm',
        'mkv' => 'video/x-matroska',
        '3gp|3gpp' => 'video/3gpp', // Can also be audio
        '3g2|3gp2' => 'video/3gpp2', // Can also be audio
        // Text formats.
        'txt|asc|c|cc|h|srt' => 'text/plain',
        'csv' => 'text/csv',
        'tsv' => 'text/tab-separated-values',
        'ics' => 'text/calendar',
        'rtx' => 'text/richtext',
        'css' => 'text/css',
        'htm|html' => 'text/html',
        'vtt' => 'text/vtt',
        'dfxp' => 'application/ttaf+xml',
        // Audio formats.
        'mp3|m4a|m4b' => 'audio/mpeg',
        'ra|ram' => 'audio/x-realaudio',
        'wav' => 'audio/wav',
        'ogg|oga' => 'audio/ogg',
        'mid|midi' => 'audio/midi',
        'wma' => 'audio/x-ms-wma',
        'wax' => 'audio/x-ms-wax',
        'mka' => 'audio/x-matroska',
        // Misc application formats.
        'rtf' => 'application/rtf',
        'js' => 'application/javascript',
        'pdf' => 'application/pdf',
        'swf' => 'application/x-shockwave-flash',
        'class' => 'application/java',
        'tar' => 'application/x-tar',
        'zip' => 'application/zip',
        'gz|gzip' => 'application/x-gzip',
        'rar' => 'application/rar',
        '7z' => 'application/x-7z-compressed',
        'exe' => 'application/x-msdownload',
        'psd' => 'application/octet-stream',
        'xcf' => 'application/octet-stream',
        // MS Office formats.
        'doc' => 'application/msword',
        'pot|pps|ppt' => 'application/vnd.ms-powerpoint',
        'wri' => 'application/vnd.ms-write',
        'xla|xls|xlt|xlw' => 'application/vnd.ms-excel',
        'mdb' => 'application/vnd.ms-access',
        'mpp' => 'application/vnd.ms-project',
        'docx' => 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
        'docm' => 'application/vnd.ms-word.document.macroEnabled.12',
        'dotx' => 'application/vnd.openxmlformats-officedocument.wordprocessingml.template',
        'dotm' => 'application/vnd.ms-word.template.macroEnabled.12',
        'xlsx' => 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
        'xlsm' => 'application/vnd.ms-excel.sheet.macroEnabled.12',
        'xlsb' => 'application/vnd.ms-excel.sheet.binary.macroEnabled.12',
        'xltx' => 'application/vnd.openxmlformats-officedocument.spreadsheetml.template',
        'xltm' => 'application/vnd.ms-excel.template.macroEnabled.12',
        'xlam' => 'application/vnd.ms-excel.addin.macroEnabled.12',
        'pptx' => 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
        'pptm' => 'application/vnd.ms-powerpoint.presentation.macroEnabled.12',
        'ppsx' => 'application/vnd.openxmlformats-officedocument.presentationml.slideshow',
        'ppsm' => 'application/vnd.ms-powerpoint.slideshow.macroEnabled.12',
        'potx' => 'application/vnd.openxmlformats-officedocument.presentationml.template',
        'potm' => 'application/vnd.ms-powerpoint.template.macroEnabled.12',
        'ppam' => 'application/vnd.ms-powerpoint.addin.macroEnabled.12',
        'sldx' => 'application/vnd.openxmlformats-officedocument.presentationml.slide',
        'sldm' => 'application/vnd.ms-powerpoint.slide.macroEnabled.12',
        'onetoc|onetoc2|onetmp|onepkg' => 'application/onenote',
        'oxps' => 'application/oxps',
        'xps' => 'application/vnd.ms-xpsdocument',
        // OpenOffice formats.
        'odt' => 'application/vnd.oasis.opendocument.text',
        'odp' => 'application/vnd.oasis.opendocument.presentation',
        'ods' => 'application/vnd.oasis.opendocument.spreadsheet',
        'odg' => 'application/vnd.oasis.opendocument.graphics',
        'odc' => 'application/vnd.oasis.opendocument.chart',
        'odb' => 'application/vnd.oasis.opendocument.database',
        'odf' => 'application/vnd.oasis.opendocument.formula',
        // WordPerfect formats.
        'wp|wpd' => 'application/wordperfect',
        // iWork formats.
        'key' => 'application/vnd.apple.keynote',
        'numbers' => 'application/vnd.apple.numbers',
        'pages' => 'application/vnd.apple.pages',
    ) );
}

/**
 * Retrieves the list of common file extensions and their types.
 *
 * @since 4.6.0
 *
 * @return array Array of file extensions types keyed by the type of file.
 */
function wp_get_ext_types() {

    /**
     * Filters file type based on the extension name.
     *
     * @since 2.5.0
     *
     * @see wp_ext2type()
     *
     * @param array $ext2type Multi-dimensional array with extensions for a default set
     *                        of file types.
     */
    return apply_filters( 'ext2type', array(
        'image'       => array( 'jpg', 'jpeg', 'jpe',  'gif',  'png',  'bmp',   'tif',  'tiff', 'ico' ),
        'audio'       => array( 'aac', 'ac3',  'aif',  'aiff', 'm3a',  'm4a',   'm4b',  'mka',  'mp1',  'mp2',  'mp3', 'ogg', 'oga', 'ram', 'wav', 'wma' ),
        'video'       => array( '3g2',  '3gp', '3gpp', 'asf', 'avi',  'divx', 'dv',   'flv',  'm4v',   'mkv',  'mov',  'mp4',  'mpeg', 'mpg', 'mpv', 'ogm', 'ogv', 'qt',  'rm', 'vob', 'wmv' ),
        'document'    => array( 'doc', 'docx', 'docm', 'dotm', 'odt',  'pages', 'pdf',  'xps',  'oxps', 'rtf',  'wp', 'wpd', 'psd', 'xcf' ),
        'spreadsheet' => array( 'numbers',     'ods',  'xls',  'xlsx', 'xlsm',  'xlsb' ),
        'interactive' => array( 'swf', 'key',  'ppt',  'pptx', 'pptm', 'pps',   'ppsx', 'ppsm', 'sldx', 'sldm', 'odp' ),
        'text'        => array( 'asc', 'csv',  'tsv',  'txt' ),
        'archive'     => array( 'bz2', 'cab',  'dmg',  'gz',   'rar',  'sea',   'sit',  'sqx',  'tar',  'tgz',  'zip', '7z' ),
        'code'        => array( 'css', 'htm',  'html', 'php',  'js' ),
    ) );
}

/**
 * Retrieve list of allowed mime types and file extensions.
 *
 * @since 2.8.6
 *
 * @param int|WP_User $user Optional. User to check. Defaults to current user.
 * @return array Array of mime types keyed by the file extension regex corresponding
 *               to those types.
 */
function get_allowed_mime_types( $user = null ) {
    $t = wp_get_mime_types();

    unset( $t['swf'], $t['exe'] );
    if ( function_exists( 'current_user_can' ) )
        $unfiltered = $user ? user_can( $user, 'unfiltered_html' ) : current_user_can( 'unfiltered_html' );

    if ( empty( $unfiltered ) )
        unset( $t['htm|html'] );

    /**
     * Filters list of allowed mime types and file extensions.
     *
     * @since 2.0.0
     *
     * @param array            $t    Mime types keyed by the file extension regex corresponding to
     *                               those types. 'swf' and 'exe' removed from full list. 'htm|html' also
     *                               removed depending on '$user' capabilities.
     * @param int|WP_User|null $user User ID, User object or null if not provided (indicates current user).
     */
    return apply_filters( 'upload_mimes', $t, $user );
}

/**
 * Display "Are You Sure" message to confirm the action being taken.
 *
 * If the action has the nonce explain message, then it will be displayed
 * along with the "Are you sure?" message.
 *
 * @since 2.0.4
 *
 * @param string $action The nonce action.
 */
function wp_nonce_ays( $action ) {
    if ( 'log-out' == $action ) {
        $html = sprintf(
        /* translators: %s: site name */
            __( 'You are attempting to log out of %s' ),
            get_bloginfo( 'name' )
        );
        $html .= '</p><p>';
        $redirect_to = isset( $_REQUEST['redirect_to'] ) ? $_REQUEST['redirect_to'] : '';
        $html .= sprintf(
        /* translators: %s: logout URL */
            __( 'Do you really want to <a href="%s">log out</a>?' ),
            wp_logout_url( $redirect_to )
        );
    } else {
        $html = __( 'Are you sure you want to do this?' );
        if ( wp_get_referer() ) {
            $html .= '</p><p>';
            $html .= sprintf( '<a href="%s">%s</a>',
                esc_url( remove_query_arg( 'updated', wp_get_referer() ) ),
                __( 'Please try again.' )
            );
        }
    }

    wp_die( $html, __( 'WordPress Failure Notice' ), 403 );
}

/**
 * Kill WordPress execution and display HTML message with error message.
 *
 * This function complements the `die()` PHP function. The difference is that
 * HTML will be displayed to the user. It is recommended to use this function
 * only when the execution should not continue any further. It is not recommended
 * to call this function very often, and try to handle as many errors as possible
 * silently or more gracefully.
 *
 * As a shorthand, the desired HTTP response code may be passed as an integer to
 * the `$title` parameter (the default title would apply) or the `$args` parameter.
 *
 * @since 2.0.4
 * @since 4.1.0 The `$title` and `$args` parameters were changed to optionally accept
 *              an integer to be used as the response code.
 *
 * @param string|WP_Error  $message Optional. Error message. If this is a WP_Error object,
 *                                  and not an Ajax or XML-RPC request, the error's messages are used.
 *                                  Default empty.
 * @param string|int       $title   Optional. Error title. If `$message` is a `WP_Error` object,
 *                                  error data with the key 'title' may be used to specify the title.
 *                                  If `$title` is an integer, then it is treated as the response
 *                                  code. Default empty.
 * @param string|array|int $args {
 *     Optional. Arguments to control behavior. If `$args` is an integer, then it is treated
 *     as the response code. Default empty array.
 *
 *     @type int    $response       The HTTP response code. Default 200 for Ajax requests, 500 otherwise.
 *     @type bool   $back_link      Whether to include a link to go back. Default false.
 *     @type string $text_direction The text direction. This is only useful internally, when WordPress
 *                                  is still loading and the site's locale is not set up yet. Accepts 'rtl'.
 *                                  Default is the value of is_rtl().
 * }
 */
function wp_die( $message = '', $title = '', $args = array() ) {

    if ( is_int( $args ) ) {
        $args = array( 'response' => $args );
    } elseif ( is_int( $title ) ) {
        $args  = array( 'response' => $title );
        $title = '';
    }

    if ( wp_doing_ajax() ) {
        /**
         * Filters the callback for killing WordPress execution for Ajax requests.
         *
         * @since 3.4.0
         *
         * @param callable $function Callback function name.
         */
        $function = apply_filters( 'wp_die_ajax_handler', '_ajax_wp_die_handler' );
    } elseif ( defined( 'XMLRPC_REQUEST' ) && XMLRPC_REQUEST ) {
        /**
         * Filters the callback for killing WordPress execution for XML-RPC requests.
         *
         * @since 3.4.0
         *
         * @param callable $function Callback function name.
         */
        $function = apply_filters( 'wp_die_xmlrpc_handler', '_xmlrpc_wp_die_handler' );
    } else {
        /**
         * Filters the callback for killing WordPress execution for all non-Ajax, non-XML-RPC requests.
         *
         * @since 3.0.0
         *
         * @param callable $function Callback function name.
         */
        $function = apply_filters( 'wp_die_handler', '_default_wp_die_handler' );
    }

    call_user_func( $function, $message, $title, $args );
}

/**
 * Kills WordPress execution and display HTML message with error message.
 *
 * This is the default handler for wp_die if you want a custom one for your
 * site then you can overload using the {@see 'wp_die_handler'} filter in wp_die().
 *
 * @since 3.0.0
 * @access private
 *
 * @param string|WP_Error $message Error message or WP_Error object.
 * @param string          $title   Optional. Error title. Default empty.
 * @param string|array    $args    Optional. Arguments to control behavior. Default empty array.
 */
function _default_wp_die_handler( $message, $title = '', $args = array() ) {
    $defaults = array( 'response' => 500 );
    $r = wp_parse_args($args, $defaults);

    $have_gettext = function_exists('__');

    if ( function_exists( 'is_wp_error' ) && is_wp_error( $message ) ) {
        if ( empty( $title ) ) {
            $error_data = $message->get_error_data();
            if ( is_array( $error_data ) && isset( $error_data['title'] ) )
                $title = $error_data['title'];
        }
        $errors = $message->get_error_messages();
        switch ( count( $errors ) ) {
            case 0 :
                $message = '';
                break;
            case 1 :
                $message = "<p>{$errors[0]}</p>";
                break;
            default :
                $message = "<ul>\n\t\t<li>" . join( "</li>\n\t\t<li>", $errors ) . "</li>\n\t</ul>";
                break;
        }
    } elseif ( is_string( $message ) ) {
        $message = "<p>$message</p>";
    }

    if ( isset( $r['back_link'] ) && $r['back_link'] ) {
        $back_text = $have_gettext? __('&laquo; Back') : '&laquo; Back';
        $message .= "\n<p><a href='javascript:history.back()'>$back_text</a></p>";
    }

    if ( ! did_action( 'admin_head' ) ) :
        if ( !headers_sent() ) {
            status_header( $r['response'] );
            nocache_headers();
            header( 'Content-Type: text/html; charset=utf-8' );
        }

        if ( empty($title) )
            $title = $have_gettext ? __('WordPress &rsaquo; Error') : 'WordPress &rsaquo; Error';

        $text_direction = 'ltr';
        if ( isset($r['text_direction']) && 'rtl' == $r['text_direction'] )
            $text_direction = 'rtl';
        elseif ( function_exists( 'is_rtl' ) && is_rtl() )
            $text_direction = 'rtl';
        ?>
        <!DOCTYPE html>
        <!-- Ticket #11289, IE bug fix: always pad the error page with enough characters such that it is greater than 512 bytes, even after gzip compression abcdefghijklmnopqrstuvwxyz1234567890aabbccddeeffgghhiijjkkllmmnnooppqqrrssttuuvvwwxxyyzz11223344556677889900abacbcbdcdcededfefegfgfhghgihihjijikjkjlklkmlmlnmnmononpopoqpqprqrqsrsrtstsubcbcdcdedefefgfabcadefbghicjkldmnoepqrfstugvwxhyz1i234j567k890laabmbccnddeoeffpgghqhiirjjksklltmmnunoovppqwqrrxsstytuuzvvw0wxx1yyz2z113223434455666777889890091abc2def3ghi4jkl5mno6pqr7stu8vwx9yz11aab2bcc3dd4ee5ff6gg7hh8ii9j0jk1kl2lmm3nnoo4p5pq6qrr7ss8tt9uuvv0wwx1x2yyzz13aba4cbcb5dcdc6dedfef8egf9gfh0ghg1ihi2hji3jik4jkj5lkl6kml7mln8mnm9ono
        -->
        <html xmlns="http://www.w3.org/1999/xhtml" <?php if ( function_exists( 'language_attributes' ) && function_exists( 'is_rtl' ) ) language_attributes(); else echo "dir='$text_direction'"; ?>>
        <head>
            <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
            <meta name="viewport" content="width=device-width">
            <?php
            if ( function_exists( 'wp_no_robots' ) ) {
                wp_no_robots();
            }
            ?>
            <title><?php echo $title ?></title>
            <style type="text/css">
                html {
                    background: #f1f1f1;
                }
                body {
                    background: #fff;
                    color: #444;
                    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
                    margin: 2em auto;
                    padding: 1em 2em;
                    max-width: 700px;
                    -webkit-box-shadow: 0 1px 3px rgba(0,0,0,0.13);
                    box-shadow: 0 1px 3px rgba(0,0,0,0.13);
                }
                h1 {
                    border-bottom: 1px solid #dadada;
                    clear: both;
                    color: #666;
                    font-size: 24px;
                    margin: 30px 0 0 0;
                    padding: 0;
                    padding-bottom: 7px;
                }
                #error-page {
                    margin-top: 50px;
                }
                #error-page p {
                    font-size: 14px;
                    line-height: 1.5;
                    margin: 25px 0 20px;
                }
                #error-page code {
                    font-family: Consolas, Monaco, monospace;
                }
                ul li {
                    margin-bottom: 10px;
                    font-size: 14px ;
                }
                a {
                    color: #0073aa;
                }
                a:hover,
                a:active {
                    color: #00a0d2;
                }
                a:focus {
                    color: #124964;
                    -webkit-box-shadow:
                            0 0 0 1px #5b9dd9,
                            0 0 2px 1px rgba(30, 140, 190, .8);
                    box-shadow:
                            0 0 0 1px #5b9dd9,
                            0 0 2px 1px rgba(30, 140, 190, .8);
                    outline: none;
                }
                .button {
                    background: #f7f7f7;
                    border: 1px solid #ccc;
                    color: #555;
                    display: inline-block;
                    text-decoration: none;
                    font-size: 13px;
                    line-height: 26px;
                    height: 28px;
                    margin: 0;
                    padding: 0 10px 1px;
                    cursor: pointer;
                    -webkit-border-radius: 3px;
                    -webkit-appearance: none;
                    border-radius: 3px;
                    white-space: nowrap;
                    -webkit-box-sizing: border-box;
                    -moz-box-sizing:    border-box;
                    box-sizing:         border-box;

                    -webkit-box-shadow: 0 1px 0 #ccc;
                    box-shadow: 0 1px 0 #ccc;
                    vertical-align: top;
                }

                .button.button-large {
                    height: 30px;
                    line-height: 28px;
                    padding: 0 12px 2px;
                }

                .button:hover,
                .button:focus {
                    background: #fafafa;
                    border-color: #999;
                    color: #23282d;
                }

                .button:focus  {
                    border-color: #5b9dd9;
                    -webkit-box-shadow: 0 0 3px rgba( 0, 115, 170, .8 );
                    box-shadow: 0 0 3px rgba( 0, 115, 170, .8 );
                    outline: none;
                }

                .button:active {
                    background: #eee;
                    border-color: #999;
                    -webkit-box-shadow: inset 0 2px 5px -3px rgba( 0, 0, 0, 0.5 );
                    box-shadow: inset 0 2px 5px -3px rgba( 0, 0, 0, 0.5 );
                    -webkit-transform: translateY(1px);
                    -ms-transform: translateY(1px);
                    transform: translateY(1px);
                }

                <?php
                if ( 'rtl' == $text_direction ) {
                    echo 'body { font-family: Tahoma, Arial; }';
                }
                ?>
            </style>
        </head>
        <body id="error-page">
    <?php endif; // ! did_action( 'admin_head' ) ?>
    <?php echo $message; ?>
</body>
    </html>
    <?php
    die();
}

/**
 * Kill WordPress execution and display XML message with error message.
 *
 * This is the handler for wp_die when processing XMLRPC requests.
 *
 * @since 3.2.0
 * @access private
 *
 * @global wp_xmlrpc_server $wp_xmlrpc_server
 *
 * @param string       $message Error message.
 * @param string       $title   Optional. Error title. Default empty.
 * @param string|array $args    Optional. Arguments to control behavior. Default empty array.
 */
function _xmlrpc_wp_die_handler( $message, $title = '', $args = array() ) {
    global $wp_xmlrpc_server;
    $defaults = array( 'response' => 500 );

    $r = wp_parse_args($args, $defaults);

    if ( $wp_xmlrpc_server ) {
        $error = new IXR_Error( $r['response'] , $message);
        $wp_xmlrpc_server->output( $error->getXml() );
    }
    die();
}

/**
 * Kill WordPress ajax execution.
 *
 * This is the handler for wp_die when processing Ajax requests.
 *
 * @since 3.4.0
 * @access private
 *
 * @param string       $message Error message.
 * @param string       $title   Optional. Error title (unused). Default empty.
 * @param string|array $args    Optional. Arguments to control behavior. Default empty array.
 */
function _ajax_wp_die_handler( $message, $title = '', $args = array() ) {
    $defaults = array(
        'response' => 200,
    );
    $r = wp_parse_args( $args, $defaults );

    if ( ! headers_sent() && null !== $r['response'] ) {
        status_header( $r['response'] );
    }

    if ( is_scalar( $message ) )
        die( (string) $message );
    die( '0' );
}

/**
 * Kill WordPress execution.
 *
 * This is the handler for wp_die when processing APP requests.
 *
 * @since 3.4.0
 * @access private
 *
 * @param string $message Optional. Response to print. Default empty.
 */
function _scalar_wp_die_handler( $message = '' ) {
    if ( is_scalar( $message ) )
        die( (string) $message );
    die();
}

/**
 * Encode a variable into JSON, with some sanity checks.
 *
 * @since 4.1.0
 *
 * @param mixed $data    Variable (usually an array or object) to encode as JSON.
 * @param int   $options Optional. Options to be passed to json_encode(). Default 0.
 * @param int   $depth   Optional. Maximum depth to walk through $data. Must be
 *                       greater than 0. Default 512.
 * @return string|false The JSON encoded string, or false if it cannot be encoded.
 */
function wp_json_encode( $data, $options = 0, $depth = 512 ) {
    /*
     * json_encode() has had extra params added over the years.
     * $options was added in 5.3, and $depth in 5.5.
     * We need to make sure we call it with the correct arguments.
     */
    if ( version_compare( PHP_VERSION, '5.5', '>=' ) ) {
        $args = array( $data, $options, $depth );
    } elseif ( version_compare( PHP_VERSION, '5.3', '>=' ) ) {
        $args = array( $data, $options );
    } else {
        $args = array( $data );
    }

    // Prepare the data for JSON serialization.
    $args[0] = _wp_json_prepare_data( $data );

    $json = @call_user_func_array( 'json_encode', $args );

    // If json_encode() was successful, no need to do more sanity checking.
    // ... unless we're in an old version of PHP, and json_encode() returned
    // a string containing 'null'. Then we need to do more sanity checking.
    if ( false !== $json && ( version_compare( PHP_VERSION, '5.5', '>=' ) || false === strpos( $json, 'null' ) ) )  {
        return $json;
    }

    try {
        $args[0] = _wp_json_sanity_check( $data, $depth );
    } catch ( Exception $e ) {
        return false;
    }

    return call_user_func_array( 'json_encode', $args );
}

/**
 * Perform sanity checks on data that shall be encoded to JSON.
 *
 * @ignore
 * @since 4.1.0
 * @access private
 *
 * @see wp_json_encode()
 *
 * @param mixed $data  Variable (usually an array or object) to encode as JSON.
 * @param int   $depth Maximum depth to walk through $data. Must be greater than 0.
 * @return mixed The sanitized data that shall be encoded to JSON.
 */
function _wp_json_sanity_check( $data, $depth ) {
    if ( $depth < 0 ) {
        throw new Exception( 'Reached depth limit' );
    }

    if ( is_array( $data ) ) {
        $output = array();
        foreach ( $data as $id => $el ) {
            // Don't forget to sanitize the ID!
            if ( is_string( $id ) ) {
                $clean_id = _wp_json_convert_string( $id );
            } else {
                $clean_id = $id;
            }

            // Check the element type, so that we're only recursing if we really have to.
            if ( is_array( $el ) || is_object( $el ) ) {
                $output[ $clean_id ] = _wp_json_sanity_check( $el, $depth - 1 );
            } elseif ( is_string( $el ) ) {
                $output[ $clean_id ] = _wp_json_convert_string( $el );
            } else {
                $output[ $clean_id ] = $el;
            }
        }
    } elseif ( is_object( $data ) ) {
        $output = new stdClass;
        foreach ( $data as $id => $el ) {
            if ( is_string( $id ) ) {
                $clean_id = _wp_json_convert_string( $id );
            } else {
                $clean_id = $id;
            }

            if ( is_array( $el ) || is_object( $el ) ) {
                $output->$clean_id = _wp_json_sanity_check( $el, $depth - 1 );
            } elseif ( is_string( $el ) ) {
                $output->$clean_id = _wp_json_convert_string( $el );
            } else {
                $output->$clean_id = $el;
            }
        }
    } elseif ( is_string( $data ) ) {
        return _wp_json_convert_string( $data );
    } else {
        return $data;
    }

    return $output;
}

/**
 * Convert a string to UTF-8, so that it can be safely encoded to JSON.
 *
 * @ignore
 * @since 4.1.0
 * @access private
 *
 * @see _wp_json_sanity_check()
 *
 * @staticvar bool $use_mb
 *
 * @param string $string The string which is to be converted.
 * @return string The checked string.
 */
function _wp_json_convert_string( $string ) {
    static $use_mb = null;
    if ( is_null( $use_mb ) ) {
        $use_mb = function_exists( 'mb_convert_encoding' );
    }

    if ( $use_mb ) {
        $encoding = mb_detect_encoding( $string, mb_detect_order(), true );
        if ( $encoding ) {
            return mb_convert_encoding( $string, 'UTF-8', $encoding );
        } else {
            return mb_convert_encoding( $string, 'UTF-8', 'UTF-8' );
        }
    } else {
        return wp_check_invalid_utf8( $string, true );
    }
}

/**
 * Prepares response data to be serialized to JSON.
 *
 * This supports the JsonSerializable interface for PHP 5.2-5.3 as well.
 *
 * @ignore
 * @since 4.4.0
 * @access private
 *
 * @param mixed $data Native representation.
 * @return bool|int|float|null|string|array Data ready for `json_encode()`.
 */
function _wp_json_prepare_data( $data ) {
    if ( ! defined( 'WP_JSON_SERIALIZE_COMPATIBLE' ) || WP_JSON_SERIALIZE_COMPATIBLE === false ) {
        return $data;
    }

    switch ( gettype( $data ) ) {
        case 'boolean':
        case 'integer':
        case 'double':
        case 'string':
        case 'NULL':
            // These values can be passed through.
            return $data;

        case 'array':
            // Arrays must be mapped in case they also return objects.
            return array_map( '_wp_json_prepare_data', $data );

        case 'object':
            // If this is an incomplete object (__PHP_Incomplete_Class), bail.
            if ( ! is_object( $data ) ) {
                return null;
            }

            if ( $data instanceof JsonSerializable ) {
                $data = $data->jsonSerialize();
            } else {
                $data = get_object_vars( $data );
            }

            // Now, pass the array (or whatever was returned from jsonSerialize through).
            return _wp_json_prepare_data( $data );

        default:
            return null;
    }
}

/**
 * Send a JSON response back to an Ajax request.
 *
 * @since 3.5.0
 * @since 4.7.0 The `$status_code` parameter was added.
 *
 * @param mixed $response    Variable (usually an array or object) to encode as JSON,
 *                           then print and die.
 * @param int   $status_code The HTTP status code to output.
 */
function wp_send_json( $response, $status_code = null ) {
    @header( 'Content-Type: application/json; charset=' . get_option( 'blog_charset' ) );
    if ( null !== $status_code ) {
        status_header( $status_code );
    }
    echo wp_json_encode( $response );

    if ( wp_doing_ajax() ) {
        wp_die( '', '', array(
            'response' => null,
        ) );
    } else {
        die;
    }
}

/**
 * Send a JSON response back to an Ajax request, indicating success.
 *
 * @since 3.5.0
 * @since 4.7.0 The `$status_code` parameter was added.
 *
 * @param mixed $data        Data to encode as JSON, then print and die.
 * @param int   $status_code The HTTP status code to output.
 */
function wp_send_json_success( $data = null, $status_code = null ) {
    $response = array( 'success' => true );

    if ( isset( $data ) )
        $response['data'] = $data;

    wp_send_json( $response, $status_code );
}

/**
 * Send a JSON response back to an Ajax request, indicating failure.
 *
 * If the `$data` parameter is a WP_Error object, the errors
 * within the object are processed and output as an array of error
 * codes and corresponding messages. All other types are output
 * without further processing.
 *
 * @since 3.5.0
 * @since 4.1.0 The `$data` parameter is now processed if a WP_Error object is passed in.
 * @since 4.7.0 The `$status_code` parameter was added.
 *
 * @param mixed $data        Data to encode as JSON, then print and die.
 * @param int   $status_code The HTTP status code to output.
 */
function wp_send_json_error( $data = null, $status_code = null ) {
    $response = array( 'success' => false );

    if ( isset( $data ) ) {
        if ( is_wp_error( $data ) ) {
            $result = array();
            foreach ( $data->errors as $code => $messages ) {
                foreach ( $messages as $message ) {
                    $result[] = array( 'code' => $code, 'message' => $message );
                }
            }

            $response['data'] = $result;
        } else {
            $response['data'] = $data;
        }
    }

    wp_send_json( $response, $status_code );
}

/**
 * Checks that a JSONP callback is a valid JavaScript callback.
 *
 * Only allows alphanumeric characters and the dot character in callback
 * function names. This helps to mitigate XSS attacks caused by directly
 * outputting user input.
 *
 * @since 4.6.0
 *
 * @param string $callback Supplied JSONP callback function.
 * @return bool True if valid callback, otherwise false.
 */
function wp_check_jsonp_callback( $callback ) {
    if ( ! is_string( $callback ) ) {
        return false;
    }

    preg_replace( '/[^\w\.]/', '', $callback, -1, $illegal_char_count );

    return 0 === $illegal_char_count;
}

/**
 * Retrieve the WordPress home page URL.
 *
 * If the constant named 'WP_HOME' exists, then it will be used and returned
 * by the function. This can be used to counter the redirection on your local
 * development environment.
 *
 * @since 2.2.0
 * @access private
 *
 * @see WP_HOME
 *
 * @param string $url URL for the home location.
 * @return string Homepage location.
 */
function _config_wp_home( $url = '' ) {
    if ( defined( 'WP_HOME' ) )
        return untrailingslashit( WP_HOME );
    return $url;
}

/**
 * Retrieve the WordPress site URL.
 *
 * If the constant named 'WP_SITEURL' is defined, then the value in that
 * constant will always be returned. This can be used for debugging a site
 * on your localhost while not having to change the database to your URL.
 *
 * @since 2.2.0
 * @access private
 *
 * @see WP_SITEURL
 *
 * @param string $url URL to set the WordPress site location.
 * @return string The WordPress Site URL.
 */
function _config_wp_siteurl( $url = '' ) {
    if ( defined( 'WP_SITEURL' ) )
        return untrailingslashit( WP_SITEURL );
    return $url;
}

/**
 * Delete the fresh site option.
 *
 * @since 4.7.0
 * @access private
 */
function _delete_option_fresh_site() {
    update_option( 'fresh_site', 0 );
}

/**
 * Set the localized direction for MCE plugin.
 *
 * Will only set the direction to 'rtl', if the WordPress locale has
 * the text direction set to 'rtl'.
 *
 * Fills in the 'directionality' setting, enables the 'directionality'
 * plugin, and adds the 'ltr' button to 'toolbar1', formerly
 * 'theme_advanced_buttons1' array keys. These keys are then returned
 * in the $mce_init (TinyMCE settings) array.
 *
 * @since 2.1.0
 * @access private
 *
 * @param array $mce_init MCE settings array.
 * @return array Direction set for 'rtl', if needed by locale.
 */
function _mce_set_direction( $mce_init ) {
    if ( is_rtl() ) {
        $mce_init['directionality'] = 'rtl';
        $mce_init['rtl_ui'] = true;

        if ( ! empty( $mce_init['plugins'] ) && strpos( $mce_init['plugins'], 'directionality' ) === false ) {
            $mce_init['plugins'] .= ',directionality';
        }

        if ( ! empty( $mce_init['toolbar1'] ) && ! preg_match( '/\bltr\b/', $mce_init['toolbar1'] ) ) {
            $mce_init['toolbar1'] .= ',ltr';
        }
    }

    return $mce_init;
}


/**
 * Convert smiley code to the icon graphic file equivalent.
 *
 * You can turn off smilies, by going to the write setting screen and unchecking
 * the box, or by setting 'use_smilies' option to false or removing the option.
 *
 * Plugins may override the default smiley list by setting the $wpsmiliestrans
 * to an array, with the key the code the blogger types in and the value the
 * image file.
 *
 * The $wp_smiliessearch global is for the regular expression and is set each
 * time the function is called.
 *
 * The full list of smilies can be found in the function and won't be listed in
 * the description. Probably should create a Codex page for it, so that it is
 * available.
 *
 * @global array $wpsmiliestrans
 * @global array $wp_smiliessearch
 *
 * @since 2.2.0
 */
function smilies_init() {
    global $wpsmiliestrans, $wp_smiliessearch;

    // don't bother setting up smilies if they are disabled
    if ( !get_option( 'use_smilies' ) )
        return;

    if ( !isset( $wpsmiliestrans ) ) {
        $wpsmiliestrans = array(
            ':mrgreen:' => 'mrgreen.png',
            ':neutral:' => "\xf0\x9f\x98\x90",
            ':twisted:' => "\xf0\x9f\x98\x88",
            ':arrow:' => "\xe2\x9e\xa1",
            ':shock:' => "\xf0\x9f\x98\xaf",
            ':smile:' => "\xf0\x9f\x99\x82",
            ':???:' => "\xf0\x9f\x98\x95",
            ':cool:' => "\xf0\x9f\x98\x8e",
            ':evil:' => "\xf0\x9f\x91\xbf",
            ':grin:' => "\xf0\x9f\x98\x80",
            ':idea:' => "\xf0\x9f\x92\xa1",
            ':oops:' => "\xf0\x9f\x98\xb3",
            ':razz:' => "\xf0\x9f\x98\x9b",
            ':roll:' => "\xf0\x9f\x99\x84",
            ':wink:' => "\xf0\x9f\x98\x89",
            ':cry:' => "\xf0\x9f\x98\xa5",
            ':eek:' => "\xf0\x9f\x98\xae",
            ':lol:' => "\xf0\x9f\x98\x86",
            ':mad:' => "\xf0\x9f\x98\xa1",
            ':sad:' => "\xf0\x9f\x99\x81",
            '8-)' => "\xf0\x9f\x98\x8e",
            '8-O' => "\xf0\x9f\x98\xaf",
            ':-(' => "\xf0\x9f\x99\x81",
            ':-)' => "\xf0\x9f\x99\x82",
            ':-?' => "\xf0\x9f\x98\x95",
            ':-D' => "\xf0\x9f\x98\x80",
            ':-P' => "\xf0\x9f\x98\x9b",
            ':-o' => "\xf0\x9f\x98\xae",
            ':-x' => "\xf0\x9f\x98\xa1",
            ':-|' => "\xf0\x9f\x98\x90",
            ';-)' => "\xf0\x9f\x98\x89",
            // This one transformation breaks regular text with frequency.
            //     '8)' => "\xf0\x9f\x98\x8e",
            '8O' => "\xf0\x9f\x98\xaf",
            ':(' => "\xf0\x9f\x99\x81",
            ':)' => "\xf0\x9f\x99\x82",
            ':?' => "\xf0\x9f\x98\x95",
            ':D' => "\xf0\x9f\x98\x80",
            ':P' => "\xf0\x9f\x98\x9b",
            ':o' => "\xf0\x9f\x98\xae",
            ':x' => "\xf0\x9f\x98\xa1",
            ':|' => "\xf0\x9f\x98\x90",
            ';)' => "\xf0\x9f\x98\x89",
            ':!:' => "\xe2\x9d\x97",
            ':?:' => "\xe2\x9d\x93",
        );
    }

    /**
     * Filters all the smilies.
     *
     * This filter must be added before `smilies_init` is run, as
     * it is normally only run once to setup the smilies regex.
     *
     * @since 4.7.0
     *
     * @param array $wpsmiliestrans List of the smilies.
     */
    $wpsmiliestrans = apply_filters('smilies', $wpsmiliestrans);

    if (count($wpsmiliestrans) == 0) {
        return;
    }

    /*
     * NOTE: we sort the smilies in reverse key order. This is to make sure
     * we match the longest possible smilie (:???: vs :?) as the regular
     * expression used below is first-match
     */
    krsort($wpsmiliestrans);

    $spaces = wp_spaces_regexp();

    // Begin first "subpattern"
    $wp_smiliessearch = '/(?<=' . $spaces . '|^)';

    $subchar = '';
    foreach ( (array) $wpsmiliestrans as $smiley => $img ) {
        $firstchar = substr($smiley, 0, 1);
        $rest = substr($smiley, 1);

        // new subpattern?
        if ($firstchar != $subchar) {
            if ($subchar != '') {
                $wp_smiliessearch .= ')(?=' . $spaces . '|$)';  // End previous "subpattern"
                $wp_smiliessearch .= '|(?<=' . $spaces . '|^)'; // Begin another "subpattern"
            }
            $subchar = $firstchar;
            $wp_smiliessearch .= preg_quote($firstchar, '/') . '(?:';
        } else {
            $wp_smiliessearch .= '|';
        }
        $wp_smiliessearch .= preg_quote($rest, '/');
    }

    $wp_smiliessearch .= ')(?=' . $spaces . '|$)/m';

}

/**
 * Merge user defined arguments into defaults array.
 *
 * This function is used throughout WordPress to allow for both string or array
 * to be merged into another array.
 *
 * @since 2.2.0
 * @since 2.3.0 `$args` can now also be an object.
 *
 * @param string|array|object $args     Value to merge with $defaults.
 * @param array               $defaults Optional. Array that serves as the defaults. Default empty.
 * @return array Merged user defined values with defaults.
 */
function wp_parse_args( $args, $defaults = '' ) {
    if ( is_object( $args ) )
        $r = get_object_vars( $args );
    elseif ( is_array( $args ) )
        $r =& $args;
    else
        wp_parse_str( $args, $r );

    if ( is_array( $defaults ) )
        return array_merge( $defaults, $r );
    return $r;
}

/**
 * Clean up an array, comma- or space-separated list of IDs.
 *
 * @since 3.0.0
 *
 * @param array|string $list List of ids.
 * @return array Sanitized array of IDs.
 */
function wp_parse_id_list( $list ) {
    if ( !is_array($list) )
        $list = preg_split('/[\s,]+/', $list);

    return array_unique(array_map('absint', $list));
}

/**
 * Clean up an array, comma- or space-separated list of slugs.
 *
 * @since 4.7.0
 *
 * @param  array|string $list List of slugs.
 * @return array Sanitized array of slugs.
 */
function wp_parse_slug_list( $list ) {
    if ( ! is_array( $list ) ) {
        $list = preg_split( '/[\s,]+/', $list );
    }

    foreach ( $list as $key => $value ) {
        $list[ $key ] = sanitize_title( $value );
    }

    return array_unique( $list );
}

/**
 * Extract a slice of an array, given a list of keys.
 *
 * @since 3.1.0
 *
 * @param array $array The original array.
 * @param array $keys  The list of keys.
 * @return array The array slice.
 */
function wp_array_slice_assoc( $array, $keys ) {
    $slice = array();
    foreach ( $keys as $key )
        if ( isset( $array[ $key ] ) )
            $slice[ $key ] = $array[ $key ];

    return $slice;
}

/**
 * Determines if the variable is a numeric-indexed array.
 *
 * @since 4.4.0
 *
 * @param mixed $data Variable to check.
 * @return bool Whether the variable is a list.
 */
function wp_is_numeric_array( $data ) {
    if ( ! is_array( $data ) ) {
        return false;
    }

    $keys = array_keys( $data );
    $string_keys = array_filter( $keys, 'is_string' );
    return count( $string_keys ) === 0;
}

/**
 * Filters a list of objects, based on a set of key => value arguments.
 *
 * @since 3.0.0
 * @since 4.7.0 Uses WP_List_Util class.
 *
 * @param array       $list     An array of objects to filter
 * @param array       $args     Optional. An array of key => value arguments to match
 *                              against each object. Default empty array.
 * @param string      $operator Optional. The logical operation to perform. 'or' means
 *                              only one element from the array needs to match; 'and'
 *                              means all elements must match; 'not' means no elements may
 *                              match. Default 'and'.
 * @param bool|string $field    A field from the object to place instead of the entire object.
 *                              Default false.
 * @return array A list of objects or object fields.
 */
function wp_filter_object_list( $list, $args = array(), $operator = 'and', $field = false ) {
    if ( ! is_array( $list ) ) {
        return array();
    }

    $util = new WP_List_Util( $list );

    $util->filter( $args, $operator );

    if ( $field ) {
        $util->pluck( $field );
    }

    return $util->get_output();
}

/**
 * Filters a list of objects, based on a set of key => value arguments.
 *
 * @since 3.1.0
 * @since 4.7.0 Uses WP_List_Util class.
 *
 * @param array  $list     An array of objects to filter.
 * @param array  $args     Optional. An array of key => value arguments to match
 *                         against each object. Default empty array.
 * @param string $operator Optional. The logical operation to perform. 'AND' means
 *                         all elements from the array must match. 'OR' means only
 *                         one element needs to match. 'NOT' means no elements may
 *                         match. Default 'AND'.
 * @return array Array of found values.
 */
function wp_list_filter( $list, $args = array(), $operator = 'AND' ) {
    if ( ! is_array( $list ) ) {
        return array();
    }

    $util = new WP_List_Util( $list );
    return $util->filter( $args, $operator );
}

/**
 * Pluck a certain field out of each object in a list.
 *
 * This has the same functionality and prototype of
 * array_column() (PHP 5.5) but also supports objects.
 *
 * @since 3.1.0
 * @since 4.0.0 $index_key parameter added.
 * @since 4.7.0 Uses WP_List_Util class.
 *
 * @param array      $list      List of objects or arrays
 * @param int|string $field     Field from the object to place instead of the entire object
 * @param int|string $index_key Optional. Field from the object to use as keys for the new array.
 *                              Default null.
 * @return array Array of found values. If `$index_key` is set, an array of found values with keys
 *               corresponding to `$index_key`. If `$index_key` is null, array keys from the original
 *               `$list` will be preserved in the results.
 */
function wp_list_pluck( $list, $field, $index_key = null ) {
    $util = new WP_List_Util( $list );
    return $util->pluck( $field, $index_key );
}

/**
 * Sorts a list of objects, based on one or more orderby arguments.
 *
 * @since 4.7.0
 *
 * @param array        $list          An array of objects to filter.
 * @param string|array $orderby       Optional. Either the field name to order by or an array
 *                                    of multiple orderby fields as $orderby => $order.
 * @param string       $order         Optional. Either 'ASC' or 'DESC'. Only used if $orderby
 *                                    is a string.
 * @param bool         $preserve_keys Optional. Whether to preserve keys. Default false.
 * @return array The sorted array.
 */
function wp_list_sort( $list, $orderby = array(), $order = 'ASC', $preserve_keys = false ) {
    if ( ! is_array( $list ) ) {
        return array();
    }

    $util = new WP_List_Util( $list );
    return $util->sort( $orderby, $order, $preserve_keys );
}

/**
 * Determines if Widgets library should be loaded.
 *
 * Checks to make sure that the widgets library hasn't already been loaded.
 * If it hasn't, then it will load the widgets library and run an action hook.
 *
 * @since 2.2.0
 */
function wp_maybe_load_widgets() {
    /**
     * Filters whether to load the Widgets library.
     *
     * Passing a falsey value to the filter will effectively short-circuit
     * the Widgets library from loading.
     *
     * @since 2.8.0
     *
     * @param bool $wp_maybe_load_widgets Whether to load the Widgets library.
     *                                    Default true.
     */
    if ( ! apply_filters( 'load_default_widgets', true ) ) {
        return;
    }

    require_once( ABSPATH . WPINC . '/default-widgets.php' );

    add_action( '_admin_menu', 'wp_widgets_add_menu' );
}

/**
 * Append the Widgets menu to the themes main menu.
 *
 * @since 2.2.0
 *
 * @global array $submenu
 */
function wp_widgets_add_menu() {
    global $submenu;

    if ( ! current_theme_supports( 'widgets' ) )
        return;

    $submenu['themes.php'][7] = array( __( 'Widgets' ), 'edit_theme_options', 'widgets.php' );
    ksort( $submenu['themes.php'], SORT_NUMERIC );
}

/**
 * Flush all output buffers for PHP 5.2.
 *
 * Make sure all output buffers are flushed before our singletons are destroyed.
 *
 * @since 2.2.0
 */
function wp_ob_end_flush_all() {
    $levels = ob_get_level();
    for ($i=0; $i<$levels; $i++)
        ob_end_flush();
}

/**
 * Load custom DB error or display WordPress DB error.
 *
 * If a file exists in the wp-content directory named db-error.php, then it will
 * be loaded instead of displaying the WordPress DB error. If it is not found,
 * then the WordPress DB error will be displayed instead.
 *
 * The WordPress DB error sets the HTTP status header to 500 to try to prevent
 * search engines from caching the message. Custom DB messages should do the
 * same.
 *
 * This function was backported to WordPress 2.3.2, but originally was added
 * in WordPress 2.5.0.
 *
 * @since 2.3.2
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 */
function dead_db() {
    global $wpdb;

    wp_load_translations_early();

    // Load custom DB error template, if present.
    if ( file_exists( WP_CONTENT_DIR . '/db-error.php' ) ) {
        require_once( WP_CONTENT_DIR . '/db-error.php' );
        die();
    }

    // If installing or in the admin, provide the verbose message.
    if ( wp_installing() || defined( 'WP_ADMIN' ) )
        wp_die($wpdb->error);

    // Otherwise, be terse.
    status_header( 500 );
    nocache_headers();
    header( 'Content-Type: text/html; charset=utf-8' );
    ?>
    <!DOCTYPE html>
    <html xmlns="http://www.w3.org/1999/xhtml"<?php if ( is_rtl() ) echo ' dir="rtl"'; ?>>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <title><?php _e( 'Database Error' ); ?></title>

    </head>
    <body>
    <h1><?php _e( 'Error establishing a database connection' ); ?></h1>
    </body>
    </html>
    <?php
    die();
}

/**
 * Convert a value to non-negative integer.
 *
 * @since 2.5.0
 *
 * @param mixed $maybeint Data you wish to have converted to a non-negative integer.
 * @return int A non-negative integer.
 */
function absint( $maybeint ) {
    return abs( intval( $maybeint ) );
}

/**
 * Mark a function as deprecated and inform when it has been used.
 *
 * There is a {@see 'hook deprecated_function_run'} that will be called that can be used
 * to get the backtrace up to what file and function called the deprecated
 * function.
 *
 * The current behavior is to trigger a user error if `WP_DEBUG` is true.
 *
 * This function is to be used in every function that is deprecated.
 *
 * @since 2.5.0
 * @access private
 *
 * @param string $function    The function that was called.
 * @param string $version     The version of WordPress that deprecated the function.
 * @param string $replacement Optional. The function that should have been called. Default null.
 */
function _deprecated_function( $function, $version, $replacement = null ) {

    /**
     * Fires when a deprecated function is called.
     *
     * @since 2.5.0
     *
     * @param string $function    The function that was called.
     * @param string $replacement The function that should have been called.
     * @param string $version     The version of WordPress that deprecated the function.
     */
    do_action( 'deprecated_function_run', $function, $replacement, $version );

    /**
     * Filters whether to trigger an error for deprecated functions.
     *
     * @since 2.5.0
     *
     * @param bool $trigger Whether to trigger the error for deprecated functions. Default true.
     */
    if ( WP_DEBUG && apply_filters( 'deprecated_function_trigger_error', true ) ) {
        if ( function_exists( '__' ) ) {
            if ( ! is_null( $replacement ) ) {
                /* translators: 1: PHP function name, 2: version number, 3: alternative function name */
                trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.'), $function, $version, $replacement ) );
            } else {
                /* translators: 1: PHP function name, 2: version number */
                trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.'), $function, $version ) );
            }
        } else {
            if ( ! is_null( $replacement ) ) {
                trigger_error( sprintf( '%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.', $function, $version, $replacement ) );
            } else {
                trigger_error( sprintf( '%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.', $function, $version ) );
            }
        }
    }
}

/**
 * Marks a constructor as deprecated and informs when it has been used.
 *
 * Similar to _deprecated_function(), but with different strings. Used to
 * remove PHP4 style constructors.
 *
 * The current behavior is to trigger a user error if `WP_DEBUG` is true.
 *
 * This function is to be used in every PHP4 style constructor method that is deprecated.
 *
 * @since 4.3.0
 * @since 4.5.0 Added the `$parent_class` parameter.
 *
 * @access private
 *
 * @param string $class        The class containing the deprecated constructor.
 * @param string $version      The version of WordPress that deprecated the function.
 * @param string $parent_class Optional. The parent class calling the deprecated constructor.
 *                             Default empty string.
 */
function _deprecated_constructor( $class, $version, $parent_class = '' ) {

    /**
     * Fires when a deprecated constructor is called.
     *
     * @since 4.3.0
     * @since 4.5.0 Added the `$parent_class` parameter.
     *
     * @param string $class        The class containing the deprecated constructor.
     * @param string $version      The version of WordPress that deprecated the function.
     * @param string $parent_class The parent class calling the deprecated constructor.
     */
    do_action( 'deprecated_constructor_run', $class, $version, $parent_class );

    /**
     * Filters whether to trigger an error for deprecated functions.
     *
     * `WP_DEBUG` must be true in addition to the filter evaluating to true.
     *
     * @since 4.3.0
     *
     * @param bool $trigger Whether to trigger the error for deprecated functions. Default true.
     */
    if ( WP_DEBUG && apply_filters( 'deprecated_constructor_trigger_error', true ) ) {
        if ( function_exists( '__' ) ) {
            if ( ! empty( $parent_class ) ) {
                /* translators: 1: PHP class name, 2: PHP parent class name, 3: version number, 4: __construct() method */
                trigger_error( sprintf( __( 'The called constructor method for %1$s in %2$s is <strong>deprecated</strong> since version %3$s! Use %4$s instead.' ),
                    $class, $parent_class, $version, '<pre>__construct()</pre>' ) );
            } else {
                /* translators: 1: PHP class name, 2: version number, 3: __construct() method */
                trigger_error( sprintf( __( 'The called constructor method for %1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.' ),
                    $class, $version, '<pre>__construct()</pre>' ) );
            }
        } else {
            if ( ! empty( $parent_class ) ) {
                trigger_error( sprintf( 'The called constructor method for %1$s in %2$s is <strong>deprecated</strong> since version %3$s! Use %4$s instead.',
                    $class, $parent_class, $version, '<pre>__construct()</pre>' ) );
            } else {
                trigger_error( sprintf( 'The called constructor method for %1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.',
                    $class, $version, '<pre>__construct()</pre>' ) );
            }
        }
    }

}

/**
 * Mark a file as deprecated and inform when it has been used.
 *
 * There is a hook {@see 'deprecated_file_included'} that will be called that can be used
 * to get the backtrace up to what file and function included the deprecated
 * file.
 *
 * The current behavior is to trigger a user error if `WP_DEBUG` is true.
 *
 * This function is to be used in every file that is deprecated.
 *
 * @since 2.5.0
 * @access private
 *
 * @param string $file        The file that was included.
 * @param string $version     The version of WordPress that deprecated the file.
 * @param string $replacement Optional. The file that should have been included based on ABSPATH.
 *                            Default null.
 * @param string $message     Optional. A message regarding the change. Default empty.
 */
function _deprecated_file( $file, $version, $replacement = null, $message = '' ) {

    /**
     * Fires when a deprecated file is called.
     *
     * @since 2.5.0
     *
     * @param string $file        The file that was called.
     * @param string $replacement The file that should have been included based on ABSPATH.
     * @param string $version     The version of WordPress that deprecated the file.
     * @param string $message     A message regarding the change.
     */
    do_action( 'deprecated_file_included', $file, $replacement, $version, $message );

    /**
     * Filters whether to trigger an error for deprecated files.
     *
     * @since 2.5.0
     *
     * @param bool $trigger Whether to trigger the error for deprecated files. Default true.
     */
    if ( WP_DEBUG && apply_filters( 'deprecated_file_trigger_error', true ) ) {
        $message = empty( $message ) ? '' : ' ' . $message;
        if ( function_exists( '__' ) ) {
            if ( ! is_null( $replacement ) ) {
                /* translators: 1: PHP file name, 2: version number, 3: alternative file name */
                trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.'), $file, $version, $replacement ) . $message );
            } else {
                /* translators: 1: PHP file name, 2: version number */
                trigger_error( sprintf( __('%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.'), $file, $version ) . $message );
            }
        } else {
            if ( ! is_null( $replacement ) ) {
                trigger_error( sprintf( '%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.', $file, $version, $replacement ) . $message );
            } else {
                trigger_error( sprintf( '%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.', $file, $version ) . $message );
            }
        }
    }
}
/**
 * Mark a function argument as deprecated and inform when it has been used.
 *
 * This function is to be used whenever a deprecated function argument is used.
 * Before this function is called, the argument must be checked for whether it was
 * used by comparing it to its default value or evaluating whether it is empty.
 * For example:
 *
 *     if ( ! empty( $deprecated ) ) {
 *         _deprecated_argument( __FUNCTION__, '3.0.0' );
 *     }
 *
 *
 * There is a hook deprecated_argument_run that will be called that can be used
 * to get the backtrace up to what file and function used the deprecated
 * argument.
 *
 * The current behavior is to trigger a user error if WP_DEBUG is true.
 *
 * @since 3.0.0
 * @access private
 *
 * @param string $function The function that was called.
 * @param string $version  The version of WordPress that deprecated the argument used.
 * @param string $message  Optional. A message regarding the change. Default null.
 */
function _deprecated_argument( $function, $version, $message = null ) {

    /**
     * Fires when a deprecated argument is called.
     *
     * @since 3.0.0
     *
     * @param string $function The function that was called.
     * @param string $message  A message regarding the change.
     * @param string $version  The version of WordPress that deprecated the argument used.
     */
    do_action( 'deprecated_argument_run', $function, $message, $version );

    /**
     * Filters whether to trigger an error for deprecated arguments.
     *
     * @since 3.0.0
     *
     * @param bool $trigger Whether to trigger the error for deprecated arguments. Default true.
     */
    if ( WP_DEBUG && apply_filters( 'deprecated_argument_trigger_error', true ) ) {
        if ( function_exists( '__' ) ) {
            if ( ! is_null( $message ) ) {
                /* translators: 1: PHP function name, 2: version number, 3: optional message regarding the change */
                trigger_error( sprintf( __('%1$s was called with an argument that is <strong>deprecated</strong> since version %2$s! %3$s'), $function, $version, $message ) );
            } else {
                /* translators: 1: PHP function name, 2: version number */
                trigger_error( sprintf( __('%1$s was called with an argument that is <strong>deprecated</strong> since version %2$s with no alternative available.'), $function, $version ) );
            }
        } else {
            if ( ! is_null( $message ) ) {
                trigger_error( sprintf( '%1$s was called with an argument that is <strong>deprecated</strong> since version %2$s! %3$s', $function, $version, $message ) );
            } else {
                trigger_error( sprintf( '%1$s was called with an argument that is <strong>deprecated</strong> since version %2$s with no alternative available.', $function, $version ) );
            }
        }
    }
}

/**
 * Marks a deprecated action or filter hook as deprecated and throws a notice.
 *
 * Use the {@see 'deprecated_hook_run'} action to get the backtrace describing where
 * the deprecated hook was called.
 *
 * Default behavior is to trigger a user error if `WP_DEBUG` is true.
 *
 * This function is called by the do_action_deprecated() and apply_filters_deprecated()
 * functions, and so generally does not need to be called directly.
 *
 * @since 4.6.0
 * @access private
 *
 * @param string $hook        The hook that was used.
 * @param string $version     The version of WordPress that deprecated the hook.
 * @param string $replacement Optional. The hook that should have been used.
 * @param string $message     Optional. A message regarding the change.
 */
function _deprecated_hook( $hook, $version, $replacement = null, $message = null ) {
    /**
     * Fires when a deprecated hook is called.
     *
     * @since 4.6.0
     *
     * @param string $hook        The hook that was called.
     * @param string $replacement The hook that should be used as a replacement.
     * @param string $version     The version of WordPress that deprecated the argument used.
     * @param string $message     A message regarding the change.
     */
    do_action( 'deprecated_hook_run', $hook, $replacement, $version, $message );

    /**
     * Filters whether to trigger deprecated hook errors.
     *
     * @since 4.6.0
     *
     * @param bool $trigger Whether to trigger deprecated hook errors. Requires
     *                      `WP_DEBUG` to be defined true.
     */
    if ( WP_DEBUG && apply_filters( 'deprecated_hook_trigger_error', true ) ) {
        $message = empty( $message ) ? '' : ' ' . $message;
        if ( ! is_null( $replacement ) ) {
            /* translators: 1: WordPress hook name, 2: version number, 3: alternative hook name */
            trigger_error( sprintf( __( '%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.' ), $hook, $version, $replacement ) . $message );
        } else {
            /* translators: 1: WordPress hook name, 2: version number */
            trigger_error( sprintf( __( '%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.' ), $hook, $version ) . $message );
        }
    }
}

/**
 * Mark something as being incorrectly called.
 *
 * There is a hook {@see 'doing_it_wrong_run'} that will be called that can be used
 * to get the backtrace up to what file and function called the deprecated
 * function.
 *
 * The current behavior is to trigger a user error if `WP_DEBUG` is true.
 *
 * @since 3.1.0
 * @access private
 *
 * @param string $function The function that was called.
 * @param string $message  A message explaining what has been done incorrectly.
 * @param string $version  The version of WordPress where the message was added.
 */
function _doing_it_wrong( $function, $message, $version ) {

    /**
     * Fires when the given function is being used incorrectly.
     *
     * @since 3.1.0
     *
     * @param string $function The function that was called.
     * @param string $message  A message explaining what has been done incorrectly.
     * @param string $version  The version of WordPress where the message was added.
     */
    do_action( 'doing_it_wrong_run', $function, $message, $version );

    /**
     * Filters whether to trigger an error for _doing_it_wrong() calls.
     *
     * @since 3.1.0
     *
     * @param bool $trigger Whether to trigger the error for _doing_it_wrong() calls. Default true.
     */
    if ( WP_DEBUG && apply_filters( 'doing_it_wrong_trigger_error', true ) ) {
        if ( function_exists( '__' ) ) {
            if ( is_null( $version ) ) {
                $version = '';
            } else {
                /* translators: %s: version number */
                $version = sprintf( __( '(This message was added in version %s.)' ), $version );
            }
            /* translators: %s: Codex URL */
            $message .= ' ' . sprintf( __( 'Please see <a href="%s">Debugging in WordPress</a> for more information.' ),
                    __( 'https://codex.wordpress.org/Debugging_in_WordPress' )
                );
            /* translators: Developer debugging message. 1: PHP function name, 2: Explanatory message, 3: Version information message */
            trigger_error( sprintf( __( '%1$s was called <strong>incorrectly</strong>. %2$s %3$s' ), $function, $message, $version ) );
        } else {
            if ( is_null( $version ) ) {
                $version = '';
            } else {
                $version = sprintf( '(This message was added in version %s.)', $version );
            }
            $message .= sprintf( ' Please see <a href="%s">Debugging in WordPress</a> for more information.',
                'https://codex.wordpress.org/Debugging_in_WordPress'
            );
            trigger_error( sprintf( '%1$s was called <strong>incorrectly</strong>. %2$s %3$s', $function, $message, $version ) );
        }
    }
}

/**
 * Is the server running earlier than 1.5.0 version of lighttpd?
 *
 * @since 2.5.0
 *
 * @return bool Whether the server is running lighttpd < 1.5.0.
 */
function is_lighttpd_before_150() {
    $server_parts = explode( '/', isset( $_SERVER['SERVER_SOFTWARE'] )? $_SERVER['SERVER_SOFTWARE'] : '' );
    $server_parts[1] = isset( $server_parts[1] )? $server_parts[1] : '';
    return  'lighttpd' == $server_parts[0] && -1 == version_compare( $server_parts[1], '1.5.0' );
}

/**
 * Does the specified module exist in the Apache config?
 *
 * @since 2.5.0
 *
 * @global bool $is_apache
 *
 * @param string $mod     The module, e.g. mod_rewrite.
 * @param bool   $default Optional. The default return value if the module is not found. Default false.
 * @return bool Whether the specified module is loaded.
 */
function apache_mod_loaded($mod, $default = false) {
    global $is_apache;

    if ( !$is_apache )
        return false;

    if ( function_exists( 'apache_get_modules' ) ) {
        $mods = apache_get_modules();
        if ( in_array($mod, $mods) )
            return true;
    } elseif ( function_exists( 'phpinfo' ) && false === strpos( ini_get( 'disable_functions' ), 'phpinfo' ) ) {
        ob_start();
        phpinfo(8);
        $phpinfo = ob_get_clean();
        if ( false !== strpos($phpinfo, $mod) )
            return true;
    }
    return $default;
}

/**
 * Check if IIS 7+ supports pretty permalinks.
 *
 * @since 2.8.0
 *
 * @global bool $is_iis7
 *
 * @return bool Whether IIS7 supports permalinks.
 */
function iis7_supports_permalinks() {
    global $is_iis7;

    $supports_permalinks = false;
    if ( $is_iis7 ) {
        /* First we check if the DOMDocument class exists. If it does not exist, then we cannot
         * easily update the xml configuration file, hence we just bail out and tell user that
         * pretty permalinks cannot be used.
         *
         * Next we check if the URL Rewrite Module 1.1 is loaded and enabled for the web site. When
         * URL Rewrite 1.1 is loaded it always sets a server variable called 'IIS_UrlRewriteModule'.
         * Lastly we make sure that PHP is running via FastCGI. This is important because if it runs
         * via ISAPI then pretty permalinks will not work.
         */
        $supports_permalinks = class_exists( 'DOMDocument', false ) && isset($_SERVER['IIS_UrlRewriteModule']) && ( PHP_SAPI == 'cgi-fcgi' );
    }

    /**
     * Filters whether IIS 7+ supports pretty permalinks.
     *
     * @since 2.8.0
     *
     * @param bool $supports_permalinks Whether IIS7 supports permalinks. Default false.
     */
    return apply_filters( 'iis7_supports_permalinks', $supports_permalinks );
}

/**
 * File validates against allowed set of defined rules.
 *
 * A return value of '1' means that the $file contains either '..' or './'. A
 * return value of '2' means that the $file contains ':' after the first
 * character. A return value of '3' means that the file is not in the allowed
 * files list.
 *
 * @since 1.2.0
 *
 * @param string $file File path.
 * @param array  $allowed_files List of allowed files.
 * @return int 0 means nothing is wrong, greater than 0 means something was wrong.
 */
function validate_file( $file, $allowed_files = '' ) {
    if ( false !== strpos( $file, '..' ) )
        return 1;

    if ( false !== strpos( $file, './' ) )
        return 1;

    if ( ! empty( $allowed_files ) && ! in_array( $file, $allowed_files ) )
        return 3;

    if (':' == substr( $file, 1, 1 ) )
        return 2;

    return 0;
}

/**
 * Whether to force SSL used for the Administration Screens.
 *
 * @since 2.6.0
 *
 * @staticvar bool $forced
 *
 * @param string|bool $force Optional. Whether to force SSL in admin screens. Default null.
 * @return bool True if forced, false if not forced.
 */
function force_ssl_admin( $force = null ) {
    static $forced = false;

    if ( !is_null( $force ) ) {
        $old_forced = $forced;
        $forced = $force;
        return $old_forced;
    }

    return $forced;
}

/**
 * Guess the URL for the site.
 *
 * Will remove wp-admin links to retrieve only return URLs not in the wp-admin
 * directory.
 *
 * @since 2.6.0
 *
 * @return string The guessed URL.
 */
function wp_guess_url() {
    if ( defined('WP_SITEURL') && '' != WP_SITEURL ) {
        $url = WP_SITEURL;
    } else {
        $abspath_fix = str_replace( '\\', '/', ABSPATH );
        $script_filename_dir = dirname( $_SERVER['SCRIPT_FILENAME'] );

        // The request is for the admin
        if ( strpos( $_SERVER['REQUEST_URI'], 'wp-admin' ) !== false || strpos( $_SERVER['REQUEST_URI'], 'wp-login.php' ) !== false ) {
            $path = preg_replace( '#/(wp-admin/.*|wp-login.php)#i', '', $_SERVER['REQUEST_URI'] );

            // The request is for a file in ABSPATH
        } elseif ( $script_filename_dir . '/' == $abspath_fix ) {
            // Strip off any file/query params in the path
            $path = preg_replace( '#/[^/]*$#i', '', $_SERVER['PHP_SELF'] );

        } else {
            if ( false !== strpos( $_SERVER['SCRIPT_FILENAME'], $abspath_fix ) ) {
                // Request is hitting a file inside ABSPATH
                $directory = str_replace( ABSPATH, '', $script_filename_dir );
                // Strip off the sub directory, and any file/query params
                $path = preg_replace( '#/' . preg_quote( $directory, '#' ) . '/[^/]*$#i', '' , $_SERVER['REQUEST_URI'] );
            } elseif ( false !== strpos( $abspath_fix, $script_filename_dir ) ) {
                // Request is hitting a file above ABSPATH
                $subdirectory = substr( $abspath_fix, strpos( $abspath_fix, $script_filename_dir ) + strlen( $script_filename_dir ) );
                // Strip off any file/query params from the path, appending the sub directory to the install
                $path = preg_replace( '#/[^/]*$#i', '' , $_SERVER['REQUEST_URI'] ) . $subdirectory;
            } else {
                $path = $_SERVER['REQUEST_URI'];
            }
        }

        $schema = is_ssl() ? 'https://' : 'http://'; // set_url_scheme() is not defined yet
        $url = $schema . $_SERVER['HTTP_HOST'] . $path;
    }

    return rtrim($url, '/');
}

/**
 * Temporarily suspend cache additions.
 *
 * Stops more data being added to the cache, but still allows cache retrieval.
 * This is useful for actions, such as imports, when a lot of data would otherwise
 * be almost uselessly added to the cache.
 *
 * Suspension lasts for a single page load at most. Remember to call this
 * function again if you wish to re-enable cache adds earlier.
 *
 * @since 3.3.0
 *
 * @staticvar bool $_suspend
 *
 * @param bool $suspend Optional. Suspends additions if true, re-enables them if false.
 * @return bool The current suspend setting
 */
function wp_suspend_cache_addition( $suspend = null ) {
    static $_suspend = false;

    if ( is_bool( $suspend ) )
        $_suspend = $suspend;

    return $_suspend;
}

/**
 * Suspend cache invalidation.
 *
 * Turns cache invalidation on and off. Useful during imports where you don't wont to do
 * invalidations every time a post is inserted. Callers must be sure that what they are
 * doing won't lead to an inconsistent cache when invalidation is suspended.
 *
 * @since 2.7.0
 *
 * @global bool $_wp_suspend_cache_invalidation
 *
 * @param bool $suspend Optional. Whether to suspend or enable cache invalidation. Default true.
 * @return bool The current suspend setting.
 */
function wp_suspend_cache_invalidation( $suspend = true ) {
    global $_wp_suspend_cache_invalidation;

    $current_suspend = $_wp_suspend_cache_invalidation;
    $_wp_suspend_cache_invalidation = $suspend;
    return $current_suspend;
}

/**
 * Determine whether a site is the main site of the current network.
 *
 * @since 3.0.0
 *
 * @param int $site_id Optional. Site ID to test. Defaults to current site.
 * @return bool True if $site_id is the main site of the network, or if not
 *              running Multisite.
 */
function is_main_site( $site_id = null ) {
    if ( ! is_multisite() )
        return true;

    if ( ! $site_id )
        $site_id = get_current_blog_id();

    return (int) $site_id === (int) get_network()->site_id;
}

/**
 * Determine whether a network is the main network of the Multisite install.
 *
 * @since 3.7.0
 *
 * @param int $network_id Optional. Network ID to test. Defaults to current network.
 * @return bool True if $network_id is the main network, or if not running Multisite.
 */
function is_main_network( $network_id = null ) {
    if ( ! is_multisite() ) {
        return true;
    }

    if ( null === $network_id ) {
        $network_id = get_current_network_id();
    }

    $network_id = (int) $network_id;

    return ( $network_id === get_main_network_id() );
}

/**
 * Get the main network ID.
 *
 * @since 4.3.0
 *
 * @return int The ID of the main network.
 */
function get_main_network_id() {
    if ( ! is_multisite() ) {
        return 1;
    }

    $current_network = get_network();

    if ( defined( 'PRIMARY_NETWORK_ID' ) ) {
        $main_network_id = PRIMARY_NETWORK_ID;
    } elseif ( isset( $current_network->id ) && 1 === (int) $current_network->id ) {
        // If the current network has an ID of 1, assume it is the main network.
        $main_network_id = 1;
    } else {
        $_networks = get_networks( array( 'fields' => 'ids', 'number' => 1 ) );
        $main_network_id = array_shift( $_networks );
    }

    /**
     * Filters the main network ID.
     *
     * @since 4.3.0
     *
     * @param int $main_network_id The ID of the main network.
     */
    return (int) apply_filters( 'get_main_network_id', $main_network_id );
}

/**
 * Determine whether global terms are enabled.
 *
 * @since 3.0.0
 *
 * @staticvar bool $global_terms
 *
 * @return bool True if multisite and global terms enabled.
 */
function global_terms_enabled() {
    if ( ! is_multisite() )
        return false;

    static $global_terms = null;
    if ( is_null( $global_terms ) ) {

        /**
         * Filters whether global terms are enabled.
         *
         * Passing a non-null value to the filter will effectively short-circuit the function,
         * returning the value of the 'global_terms_enabled' site option instead.
         *
         * @since 3.0.0
         *
         * @param null $enabled Whether global terms are enabled.
         */
        $filter = apply_filters( 'global_terms_enabled', null );
        if ( ! is_null( $filter ) )
            $global_terms = (bool) $filter;
        else
            $global_terms = (bool) get_site_option( 'global_terms_enabled', false );
    }
    return $global_terms;
}

/**
 * gmt_offset modification for smart timezone handling.
 *
 * Overrides the gmt_offset option if we have a timezone_string available.
 *
 * @since 2.8.0
 *
 * @return float|false Timezone GMT offset, false otherwise.
 */
function wp_timezone_override_offset() {
    if ( !$timezone_string = get_option( 'timezone_string' ) ) {
        return false;
    }

    $timezone_object = timezone_open( $timezone_string );
    $datetime_object = date_create();
    if ( false === $timezone_object || false === $datetime_object ) {
        return false;
    }
    return round( timezone_offset_get( $timezone_object, $datetime_object ) / HOUR_IN_SECONDS, 2 );
}

/**
 * Sort-helper for timezones.
 *
 * @since 2.9.0
 * @access private
 *
 * @param array $a
 * @param array $b
 * @return int
 */
function _wp_timezone_choice_usort_callback( $a, $b ) {
    // Don't use translated versions of Etc
    if ( 'Etc' === $a['continent'] && 'Etc' === $b['continent'] ) {
        // Make the order of these more like the old dropdown
        if ( 'GMT+' === substr( $a['city'], 0, 4 ) && 'GMT+' === substr( $b['city'], 0, 4 ) ) {
            return -1 * ( strnatcasecmp( $a['city'], $b['city'] ) );
        }
        if ( 'UTC' === $a['city'] ) {
            if ( 'GMT+' === substr( $b['city'], 0, 4 ) ) {
                return 1;
            }
            return -1;
        }
        if ( 'UTC' === $b['city'] ) {
            if ( 'GMT+' === substr( $a['city'], 0, 4 ) ) {
                return -1;
            }
            return 1;
        }
        return strnatcasecmp( $a['city'], $b['city'] );
    }
    if ( $a['t_continent'] == $b['t_continent'] ) {
        if ( $a['t_city'] == $b['t_city'] ) {
            return strnatcasecmp( $a['t_subcity'], $b['t_subcity'] );
        }
        return strnatcasecmp( $a['t_city'], $b['t_city'] );
    } else {
        // Force Etc to the bottom of the list
        if ( 'Etc' === $a['continent'] ) {
            return 1;
        }
        if ( 'Etc' === $b['continent'] ) {
            return -1;
        }
        return strnatcasecmp( $a['t_continent'], $b['t_continent'] );
    }
}

/**
 * Gives a nicely-formatted list of timezone strings.
 *
 * @since 2.9.0
 * @since 4.7.0 Added the `$locale` parameter.
 *
 * @staticvar bool $mo_loaded
 * @staticvar string $locale_loaded
 *
 * @param string $selected_zone Selected timezone.
 * @param string $locale        Optional. Locale to load the timezones in. Default current site locale.
 * @return string
 */
function wp_timezone_choice( $selected_zone, $locale = null ) {
    static $mo_loaded = false, $locale_loaded = null;

    $continents = array( 'Africa', 'America', 'Antarctica', 'Arctic', 'Asia', 'Atlantic', 'Australia', 'Europe', 'Indian', 'Pacific');

    // Load translations for continents and cities.
    if ( ! $mo_loaded || $locale !== $locale_loaded ) {
        $locale_loaded = $locale ? $locale : get_locale();
        $mofile = WP_LANG_DIR . '/continents-cities-' . $locale_loaded . '.mo';
        unload_textdomain( 'continents-cities' );
        load_textdomain( 'continents-cities', $mofile );
        $mo_loaded = true;
    }

    $zonen = array();
    foreach ( timezone_identifiers_list() as $zone ) {
        $zone = explode( '/', $zone );
        if ( !in_array( $zone[0], $continents ) ) {
            continue;
        }

        // This determines what gets set and translated - we don't translate Etc/* strings here, they are done later
        $exists = array(
            0 => ( isset( $zone[0] ) && $zone[0] ),
            1 => ( isset( $zone[1] ) && $zone[1] ),
            2 => ( isset( $zone[2] ) && $zone[2] ),
        );
        $exists[3] = ( $exists[0] && 'Etc' !== $zone[0] );
        $exists[4] = ( $exists[1] && $exists[3] );
        $exists[5] = ( $exists[2] && $exists[3] );

        $zonen[] = array(
            'continent'   => ( $exists[0] ? $zone[0] : '' ),
            'city'        => ( $exists[1] ? $zone[1] : '' ),
            'subcity'     => ( $exists[2] ? $zone[2] : '' ),
            't_continent' => ( $exists[3] ? translate( str_replace( '_', ' ', $zone[0] ), 'continents-cities' ) : '' ),
            't_city'      => ( $exists[4] ? translate( str_replace( '_', ' ', $zone[1] ), 'continents-cities' ) : '' ),
            't_subcity'   => ( $exists[5] ? translate( str_replace( '_', ' ', $zone[2] ), 'continents-cities' ) : '' )
        );
    }
    usort( $zonen, '_wp_timezone_choice_usort_callback' );

    $structure = array();

    if ( empty( $selected_zone ) ) {
        $structure[] = '<option selected="selected" value="">' . __( 'Select a city' ) . '</option>';
    }

    foreach ( $zonen as $key => $zone ) {
        // Build value in an array to join later
        $value = array( $zone['continent'] );

        if ( empty( $zone['city'] ) ) {
            // It's at the continent level (generally won't happen)
            $display = $zone['t_continent'];
        } else {
            // It's inside a continent group

            // Continent optgroup
            if ( !isset( $zonen[$key - 1] ) || $zonen[$key - 1]['continent'] !== $zone['continent'] ) {
                $label = $zone['t_continent'];
                $structure[] = '<optgroup label="'. esc_attr( $label ) .'">';
            }

            // Add the city to the value
            $value[] = $zone['city'];

            $display = $zone['t_city'];
            if ( !empty( $zone['subcity'] ) ) {
                // Add the subcity to the value
                $value[] = $zone['subcity'];
                $display .= ' - ' . $zone['t_subcity'];
            }
        }

        // Build the value
        $value = join( '/', $value );
        $selected = '';
        if ( $value === $selected_zone ) {
            $selected = 'selected="selected" ';
        }
        $structure[] = '<option ' . $selected . 'value="' . esc_attr( $value ) . '">' . esc_html( $display ) . "</option>";

        // Close continent optgroup
        if ( !empty( $zone['city'] ) && ( !isset($zonen[$key + 1]) || (isset( $zonen[$key + 1] ) && $zonen[$key + 1]['continent'] !== $zone['continent']) ) ) {
            $structure[] = '</optgroup>';
        }
    }

    // Do UTC
    $structure[] = '<optgroup label="'. esc_attr__( 'UTC' ) .'">';
    $selected = '';
    if ( 'UTC' === $selected_zone )
        $selected = 'selected="selected" ';
    $structure[] = '<option ' . $selected . 'value="' . esc_attr( 'UTC' ) . '">' . __('UTC') . '</option>';
    $structure[] = '</optgroup>';

    // Do manual UTC offsets
    $structure[] = '<optgroup label="'. esc_attr__( 'Manual Offsets' ) .'">';
    $offset_range = array (-12, -11.5, -11, -10.5, -10, -9.5, -9, -8.5, -8, -7.5, -7, -6.5, -6, -5.5, -5, -4.5, -4, -3.5, -3, -2.5, -2, -1.5, -1, -0.5,
                           0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 5.75, 6, 6.5, 7, 7.5, 8, 8.5, 8.75, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.75, 13, 13.75, 14);
    foreach ( $offset_range as $offset ) {
        if ( 0 <= $offset )
            $offset_name = '+' . $offset;
        else
            $offset_name = (string) $offset;

        $offset_value = $offset_name;
        $offset_name = str_replace(array('.25','.5','.75'), array(':15',':30',':45'), $offset_name);
        $offset_name = 'UTC' . $offset_name;
        $offset_value = 'UTC' . $offset_value;
        $selected = '';
        if ( $offset_value === $selected_zone )
            $selected = 'selected="selected" ';
        $structure[] = '<option ' . $selected . 'value="' . esc_attr( $offset_value ) . '">' . esc_html( $offset_name ) . "</option>";

    }
    $structure[] = '</optgroup>';

    return join( "\n", $structure );
}

/**
 * Strip close comment and close php tags from file headers used by WP.
 *
 * @since 2.8.0
 * @access private
 *
 * @see https://core.trac.wordpress.org/ticket/8497
 *
 * @param string $str Header comment to clean up.
 * @return string
 */
function _cleanup_header_comment( $str ) {
    return trim(preg_replace("/\s*(?:\*\/|\?>).*/", '', $str));
}

/**
 * Permanently delete comments or posts of any type that have held a status
 * of 'trash' for the number of days defined in EMPTY_TRASH_DAYS.
 *
 * The default value of `EMPTY_TRASH_DAYS` is 30 (days).
 *
 * @since 2.9.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 */
function wp_scheduled_delete() {
    global $wpdb;

    $delete_timestamp = time() - ( DAY_IN_SECONDS * EMPTY_TRASH_DAYS );

    $posts_to_delete = $wpdb->get_results($wpdb->prepare("SELECT post_id FROM $wpdb->postmeta WHERE meta_key = '_wp_trash_meta_time' AND meta_value < '%d'", $delete_timestamp), ARRAY_A);

    foreach ( (array) $posts_to_delete as $post ) {
        $post_id = (int) $post['post_id'];
        if ( !$post_id )
            continue;

        $del_post = get_post($post_id);

        if ( !$del_post || 'trash' != $del_post->post_status ) {
            delete_post_meta($post_id, '_wp_trash_meta_status');
            delete_post_meta($post_id, '_wp_trash_meta_time');
        } else {
            wp_delete_post($post_id);
        }
    }

    $comments_to_delete = $wpdb->get_results($wpdb->prepare("SELECT comment_id FROM $wpdb->commentmeta WHERE meta_key = '_wp_trash_meta_time' AND meta_value < '%d'", $delete_timestamp), ARRAY_A);

    foreach ( (array) $comments_to_delete as $comment ) {
        $comment_id = (int) $comment['comment_id'];
        if ( !$comment_id )
            continue;

        $del_comment = get_comment($comment_id);

        if ( !$del_comment || 'trash' != $del_comment->comment_approved ) {
            delete_comment_meta($comment_id, '_wp_trash_meta_time');
            delete_comment_meta($comment_id, '_wp_trash_meta_status');
        } else {
            wp_delete_comment( $del_comment );
        }
    }
}

/**
 * Retrieve metadata from a file.
 *
 * Searches for metadata in the first 8kiB of a file, such as a plugin or theme.
 * Each piece of metadata must be on its own line. Fields can not span multiple
 * lines, the value will get cut at the end of the first line.
 *
 * If the file data is not within that first 8kiB, then the author should correct
 * their plugin file and move the data headers to the top.
 *
 * @link https://codex.wordpress.org/File_Header
 *
 * @since 2.9.0
 *
 * @param string $file            Path to the file.
 * @param array  $default_headers List of headers, in the format array('HeaderKey' => 'Header Name').
 * @param string $context         Optional. If specified adds filter hook {@see 'extra_$context_headers'}.
 *                                Default empty.
 * @return array Array of file headers in `HeaderKey => Header Value` format.
 */
function get_file_data( $file, $default_headers, $context = '' ) {
    // We don't need to write to the file, so just open for reading.
    $fp = fopen( $file, 'r' );

    // Pull only the first 8kiB of the file in.
    $file_data = fread( $fp, 8192 );

    // PHP will close file handle, but we are good citizens.
    fclose( $fp );

    // Make sure we catch CR-only line endings.
    $file_data = str_replace( "\r", "\n", $file_data );

    /**
     * Filters extra file headers by context.
     *
     * The dynamic portion of the hook name, `$context`, refers to
     * the context where extra headers might be loaded.
     *
     * @since 2.9.0
     *
     * @param array $extra_context_headers Empty array by default.
     */
    if ( $context && $extra_headers = apply_filters( "extra_{$context}_headers", array() ) ) {
        $extra_headers = array_combine( $extra_headers, $extra_headers ); // keys equal values
        $all_headers = array_merge( $extra_headers, (array) $default_headers );
    } else {
        $all_headers = $default_headers;
    }

    foreach ( $all_headers as $field => $regex ) {
        if ( preg_match( '/^[ \t\/*#@]*' . preg_quote( $regex, '/' ) . ':(.*)$/mi', $file_data, $match ) && $match[1] )
            $all_headers[ $field ] = _cleanup_header_comment( $match[1] );
        else
            $all_headers[ $field ] = '';
    }

    return $all_headers;
}

/**
 * Returns true.
 *
 * Useful for returning true to filters easily.
 *
 * @since 3.0.0
 *
 * @see __return_false()
 *
 * @return true True.
 */
function __return_true() {
    return true;
}

/**
 * Returns false.
 *
 * Useful for returning false to filters easily.
 *
 * @since 3.0.0
 *
 * @see __return_true()
 *
 * @return false False.
 */
function __return_false() {
    return false;
}

/**
 * Returns 0.
 *
 * Useful for returning 0 to filters easily.
 *
 * @since 3.0.0
 *
 * @return int 0.
 */
function __return_zero() {
    return 0;
}

/**
 * Returns an empty array.
 *
 * Useful for returning an empty array to filters easily.
 *
 * @since 3.0.0
 *
 * @return array Empty array.
 */
function __return_empty_array() {
    return array();
}

/**
 * Returns null.
 *
 * Useful for returning null to filters easily.
 *
 * @since 3.4.0
 *
 * @return null Null value.
 */
function __return_null() {
    return null;
}

/**
 * Returns an empty string.
 *
 * Useful for returning an empty string to filters easily.
 *
 * @since 3.7.0
 *
 * @see __return_null()
 *
 * @return string Empty string.
 */
function __return_empty_string() {
    return '';
}

/**
 * Send a HTTP header to disable content type sniffing in browsers which support it.
 *
 * @since 3.0.0
 *
 * @see https://blogs.msdn.com/ie/archive/2008/07/02/ie8-security-part-v-comprehensive-protection.aspx
 * @see https://src.chromium.org/viewvc/chrome?view=rev&revision=6985
 */
function send_nosniff_header() {
    @header( 'X-Content-Type-Options: nosniff' );
}

/**
 * Return a MySQL expression for selecting the week number based on the start_of_week option.
 *
 * @ignore
 * @since 3.0.0
 *
 * @param string $column Database column.
 * @return string SQL clause.
 */
function _wp_mysql_week( $column ) {
    switch ( $start_of_week = (int) get_option( 'start_of_week' ) ) {
        case 1 :
            return "WEEK( $column, 1 )";
        case 2 :
        case 3 :
        case 4 :
        case 5 :
        case 6 :
            return "WEEK( DATE_SUB( $column, INTERVAL $start_of_week DAY ), 0 )";
        case 0 :
        default :
            return "WEEK( $column, 0 )";
    }
}

/**
 * Find hierarchy loops using a callback function that maps object IDs to parent IDs.
 *
 * @since 3.1.0
 * @access private
 *
 * @param callable $callback      Function that accepts ( ID, $callback_args ) and outputs parent_ID.
 * @param int      $start         The ID to start the loop check at.
 * @param int      $start_parent  The parent_ID of $start to use instead of calling $callback( $start ).
 *                                Use null to always use $callback
 * @param array    $callback_args Optional. Additional arguments to send to $callback.
 * @return array IDs of all members of loop.
 */
function wp_find_hierarchy_loop( $callback, $start, $start_parent, $callback_args = array() ) {
    $override = is_null( $start_parent ) ? array() : array( $start => $start_parent );

    if ( !$arbitrary_loop_member = wp_find_hierarchy_loop_tortoise_hare( $callback, $start, $override, $callback_args ) )
        return array();

    return wp_find_hierarchy_loop_tortoise_hare( $callback, $arbitrary_loop_member, $override, $callback_args, true );
}

/**
 * Use the "The Tortoise and the Hare" algorithm to detect loops.
 *
 * For every step of the algorithm, the hare takes two steps and the tortoise one.
 * If the hare ever laps the tortoise, there must be a loop.
 *
 * @since 3.1.0
 * @access private
 *
 * @param callable $callback      Function that accepts ( ID, callback_arg, ... ) and outputs parent_ID.
 * @param int      $start         The ID to start the loop check at.
 * @param array    $override      Optional. An array of ( ID => parent_ID, ... ) to use instead of $callback.
 *                                Default empty array.
 * @param array    $callback_args Optional. Additional arguments to send to $callback. Default empty array.
 * @param bool     $_return_loop  Optional. Return loop members or just detect presence of loop? Only set
 *                                to true if you already know the given $start is part of a loop (otherwise
 *                                the returned array might include branches). Default false.
 * @return mixed Scalar ID of some arbitrary member of the loop, or array of IDs of all members of loop if
 *               $_return_loop
 */
function wp_find_hierarchy_loop_tortoise_hare( $callback, $start, $override = array(), $callback_args = array(), $_return_loop = false ) {
    $tortoise = $hare = $evanescent_hare = $start;
    $return = array();

    // Set evanescent_hare to one past hare
    // Increment hare two steps
    while (
        $tortoise
        &&
        ( $evanescent_hare = isset( $override[$hare] ) ? $override[$hare] : call_user_func_array( $callback, array_merge( array( $hare ), $callback_args ) ) )
        &&
        ( $hare = isset( $override[$evanescent_hare] ) ? $override[$evanescent_hare] : call_user_func_array( $callback, array_merge( array( $evanescent_hare ), $callback_args ) ) )
    ) {
        if ( $_return_loop )
            $return[$tortoise] = $return[$evanescent_hare] = $return[$hare] = true;

        // tortoise got lapped - must be a loop
        if ( $tortoise == $evanescent_hare || $tortoise == $hare )
            return $_return_loop ? $return : $tortoise;

        // Increment tortoise by one step
        $tortoise = isset( $override[$tortoise] ) ? $override[$tortoise] : call_user_func_array( $callback, array_merge( array( $tortoise ), $callback_args ) );
    }

    return false;
}

/**
 * Send a HTTP header to limit rendering of pages to same origin iframes.
 *
 * @since 3.1.3
 *
 * @see https://developer.mozilla.org/en/the_x-frame-options_response_header
 */
function send_frame_options_header() {
    @header( 'X-Frame-Options: SAMEORIGIN' );
}

/**
 * Retrieve a list of protocols to allow in HTML attributes.
 *
 * @since 3.3.0
 * @since 4.3.0 Added 'webcal' to the protocols array.
 * @since 4.7.0 Added 'urn' to the protocols array.
 *
 * @see wp_kses()
 * @see esc_url()
 *
 * @staticvar array $protocols
 *
 * @return array Array of allowed protocols. Defaults to an array containing 'http', 'https',
 *               'ftp', 'ftps', 'mailto', 'news', 'irc', 'gopher', 'nntp', 'feed', 'telnet',
 *               'mms', 'rtsp', 'svn', 'tel', 'fax', 'xmpp', 'webcal', and 'urn'.
 */
function wp_allowed_protocols() {
    static $protocols = array();

    if ( empty( $protocols ) ) {
        $protocols = array( 'http', 'https', 'ftp', 'ftps', 'mailto', 'news', 'irc', 'gopher', 'nntp', 'feed', 'telnet', 'mms', 'rtsp', 'svn', 'tel', 'fax', 'xmpp', 'webcal', 'urn' );

        /**
         * Filters the list of protocols allowed in HTML attributes.
         *
         * @since 3.0.0
         *
         * @param array $protocols Array of allowed protocols e.g. 'http', 'ftp', 'tel', and more.
         */
        $protocols = apply_filters( 'kses_allowed_protocols', $protocols );
    }

    return $protocols;
}

/**
 * Return a comma-separated string of functions that have been called to get
 * to the current point in code.
 *
 * @since 3.4.0
 *
 * @see https://core.trac.wordpress.org/ticket/19589
 *
 * @param string $ignore_class Optional. A class to ignore all function calls within - useful
 *                             when you want to just give info about the callee. Default null.
 * @param int    $skip_frames  Optional. A number of stack frames to skip - useful for unwinding
 *                             back to the source of the issue. Default 0.
 * @param bool   $pretty       Optional. Whether or not you want a comma separated string or raw
 *                             array returned. Default true.
 * @return string|array Either a string containing a reversed comma separated trace or an array
 *                      of individual calls.
 */
function wp_debug_backtrace_summary( $ignore_class = null, $skip_frames = 0, $pretty = true ) {
    if ( version_compare( PHP_VERSION, '5.2.5', '>=' ) )
        $trace = debug_backtrace( false );
    else
        $trace = debug_backtrace();

    $caller = array();
    $check_class = ! is_null( $ignore_class );
    $skip_frames++; // skip this function

    foreach ( $trace as $call ) {
        if ( $skip_frames > 0 ) {
            $skip_frames--;
        } elseif ( isset( $call['class'] ) ) {
            if ( $check_class && $ignore_class == $call['class'] )
                continue; // Filter out calls

            $caller[] = "{$call['class']}{$call['type']}{$call['function']}";
        } else {
            if ( in_array( $call['function'], array( 'do_action', 'apply_filters' ) ) ) {
                $caller[] = "{$call['function']}('{$call['args'][0]}')";
            } elseif ( in_array( $call['function'], array( 'include', 'include_once', 'require', 'require_once' ) ) ) {
                $caller[] = $call['function'] . "('" . str_replace( array( WP_CONTENT_DIR, ABSPATH ) , '', $call['args'][0] ) . "')";
            } else {
                $caller[] = $call['function'];
            }
        }
    }
    if ( $pretty )
        return join( ', ', array_reverse( $caller ) );
    else
        return $caller;
}

/**
 * Retrieve ids that are not already present in the cache.
 *
 * @since 3.4.0
 * @access private
 *
 * @param array  $object_ids ID list.
 * @param string $cache_key  The cache bucket to check against.
 *
 * @return array List of ids not present in the cache.
 */
function _get_non_cached_ids( $object_ids, $cache_key ) {
    $clean = array();
    foreach ( $object_ids as $id ) {
        $id = (int) $id;
        if ( !wp_cache_get( $id, $cache_key ) ) {
            $clean[] = $id;
        }
    }

    return $clean;
}

/**
 * Test if the current device has the capability to upload files.
 *
 * @since 3.4.0
 * @access private
 *
 * @return bool Whether the device is able to upload files.
 */
function _device_can_upload() {
    if ( ! wp_is_mobile() )
        return true;

    $ua = $_SERVER['HTTP_USER_AGENT'];

    if ( strpos($ua, 'iPhone') !== false
        || strpos($ua, 'iPad') !== false
        || strpos($ua, 'iPod') !== false ) {
        return preg_match( '#OS ([\d_]+) like Mac OS X#', $ua, $version ) && version_compare( $version[1], '6', '>=' );
    }

    return true;
}

/**
 * Test if a given path is a stream URL
 *
 * @param string $path The resource path or URL.
 * @return bool True if the path is a stream URL.
 */
function wp_is_stream( $path ) {
    $wrappers = stream_get_wrappers();
    $wrappers_re = '(' . join('|', $wrappers) . ')';

    return preg_match( "!^$wrappers_re://!", $path ) === 1;
}

/**
 * Test if the supplied date is valid for the Gregorian calendar.
 *
 * @since 3.5.0
 *
 * @see checkdate()
 *
 * @param  int    $month       Month number.
 * @param  int    $day         Day number.
 * @param  int    $year        Year number.
 * @param  string $source_date The date to filter.
 * @return bool True if valid date, false if not valid date.
 */
function wp_checkdate( $month, $day, $year, $source_date ) {
    /**
     * Filters whether the given date is valid for the Gregorian calendar.
     *
     * @since 3.5.0
     *
     * @param bool   $checkdate   Whether the given date is valid.
     * @param string $source_date Date to check.
     */
    return apply_filters( 'wp_checkdate', checkdate( $month, $day, $year ), $source_date );
}

/**
 * Load the auth check for monitoring whether the user is still logged in.
 *
 * Can be disabled with remove_action( 'admin_enqueue_scripts', 'wp_auth_check_load' );
 *
 * This is disabled for certain screens where a login screen could cause an
 * inconvenient interruption. A filter called {@see 'wp_auth_check_load'} can be used
 * for fine-grained control.
 *
 * @since 3.6.0
 */
function wp_auth_check_load() {
    if ( ! is_admin() && ! is_user_logged_in() )
        return;

    if ( defined( 'IFRAME_REQUEST' ) )
        return;

    $screen = get_current_screen();
    $hidden = array( 'update', 'update-network', 'update-core', 'update-core-network', 'upgrade', 'upgrade-network', 'network' );
    $show = ! in_array( $screen->id, $hidden );

    /**
     * Filters whether to load the authentication check.
     *
     * Passing a falsey value to the filter will effectively short-circuit
     * loading the authentication check.
     *
     * @since 3.6.0
     *
     * @param bool      $show   Whether to load the authentication check.
     * @param WP_Screen $screen The current screen object.
     */
    if ( apply_filters( 'wp_auth_check_load', $show, $screen ) ) {
        wp_enqueue_style( 'wp-auth-check' );
        wp_enqueue_script( 'wp-auth-check' );

        add_action( 'admin_print_footer_scripts', 'wp_auth_check_html', 5 );
        add_action( 'wp_print_footer_scripts', 'wp_auth_check_html', 5 );
    }
}

/**
 * Output the HTML that shows the wp-login dialog when the user is no longer logged in.
 *
 * @since 3.6.0
 */
function wp_auth_check_html() {
    $login_url = wp_login_url();
    $current_domain = ( is_ssl() ? 'https://' : 'http://' ) . $_SERVER['HTTP_HOST'];
    $same_domain = ( strpos( $login_url, $current_domain ) === 0 );

    /**
     * Filters whether the authentication check originated at the same domain.
     *
     * @since 3.6.0
     *
     * @param bool $same_domain Whether the authentication check originated at the same domain.
     */
    $same_domain = apply_filters( 'wp_auth_check_same_domain', $same_domain );
    $wrap_class = $same_domain ? 'hidden' : 'hidden fallback';

    ?>
    <div id="wp-auth-check-wrap" class="<?php echo $wrap_class; ?>">
        <div id="wp-auth-check-bg"></div>
        <div id="wp-auth-check">
            <button type="button" class="wp-auth-check-close button-link"><span class="screen-reader-text"><?php _e( 'Close dialog' ); ?></span></button>
            <?php

            if ( $same_domain ) {
                ?>
                <div id="wp-auth-check-form" class="loading" data-src="<?php echo esc_url( add_query_arg( array( 'interim-login' => 1 ), $login_url ) ); ?>"></div>
                <?php
            }

            ?>
            <div class="wp-auth-fallback">
                <p><b class="wp-auth-fallback-expired" tabindex="0"><?php _e('Session expired'); ?></b></p>
                <p><a href="<?php echo esc_url( $login_url ); ?>" target="_blank"><?php _e('Please log in again.'); ?></a>
                    <?php _e('The login page will open in a new window. After logging in you can close it and return to this page.'); ?></p>
            </div>
        </div>
    </div>
    <?php
}

/**
 * Check whether a user is still logged in, for the heartbeat.
 *
 * Send a result that shows a log-in box if the user is no longer logged in,
 * or if their cookie is within the grace period.
 *
 * @since 3.6.0
 *
 * @global int $login_grace_period
 *
 * @param array $response  The Heartbeat response.
 * @return array $response The Heartbeat response with 'wp-auth-check' value set.
 */
function wp_auth_check( $response ) {
    $response['wp-auth-check'] = is_user_logged_in() && empty( $GLOBALS['login_grace_period'] );
    return $response;
}

/**
 * Return RegEx body to liberally match an opening HTML tag.
 *
 * Matches an opening HTML tag that:
 * 1. Is self-closing or
 * 2. Has no body but has a closing tag of the same name or
 * 3. Contains a body and a closing tag of the same name
 *
 * Note: this RegEx does not balance inner tags and does not attempt
 * to produce valid HTML
 *
 * @since 3.6.0
 *
 * @param string $tag An HTML tag name. Example: 'video'.
 * @return string Tag RegEx.
 */
function get_tag_regex( $tag ) {
    if ( empty( $tag ) )
        return;
    return sprintf( '<%1$s[^<]*(?:>[\s\S]*<\/%1$s>|\s*\/>)', tag_escape( $tag ) );
}

/**
 * Retrieve a canonical form of the provided charset appropriate for passing to PHP
 * functions such as htmlspecialchars() and charset html attributes.
 *
 * @since 3.6.0
 * @access private
 *
 * @see https://core.trac.wordpress.org/ticket/23688
 *
 * @param string $charset A charset name.
 * @return string The canonical form of the charset.
 */
function _canonical_charset( $charset ) {
    if ( 'utf-8' === strtolower( $charset ) || 'utf8' === strtolower( $charset) ) {

        return 'UTF-8';
    }

    if ( 'iso-8859-1' === strtolower( $charset ) || 'iso8859-1' === strtolower( $charset ) ) {

        return 'ISO-8859-1';
    }

    return $charset;
}

/**
 * Set the mbstring internal encoding to a binary safe encoding when func_overload
 * is enabled.
 *
 * When mbstring.func_overload is in use for multi-byte encodings, the results from
 * strlen() and similar functions respect the utf8 characters, causing binary data
 * to return incorrect lengths.
 *
 * This function overrides the mbstring encoding to a binary-safe encoding, and
 * resets it to the users expected encoding afterwards through the
 * `reset_mbstring_encoding` function.
 *
 * It is safe to recursively call this function, however each
 * `mbstring_binary_safe_encoding()` call must be followed up with an equal number
 * of `reset_mbstring_encoding()` calls.
 *
 * @since 3.7.0
 *
 * @see reset_mbstring_encoding()
 *
 * @staticvar array $encodings
 * @staticvar bool  $overloaded
 *
 * @param bool $reset Optional. Whether to reset the encoding back to a previously-set encoding.
 *                    Default false.
 */
function mbstring_binary_safe_encoding( $reset = false ) {
    static $encodings = array();
    static $overloaded = null;

    if ( is_null( $overloaded ) )
        $overloaded = function_exists( 'mb_internal_encoding' ) && ( ini_get( 'mbstring.func_overload' ) & 2 );

    if ( false === $overloaded )
        return;

    if ( ! $reset ) {
        $encoding = mb_internal_encoding();
        array_push( $encodings, $encoding );
        mb_internal_encoding( 'ISO-8859-1' );
    }

    if ( $reset && $encodings ) {
        $encoding = array_pop( $encodings );
        mb_internal_encoding( $encoding );
    }
}

/**
 * Reset the mbstring internal encoding to a users previously set encoding.
 *
 * @see mbstring_binary_safe_encoding()
 *
 * @since 3.7.0
 */
function reset_mbstring_encoding() {
    mbstring_binary_safe_encoding( true );
}

/**
 * Filter/validate a variable as a boolean.
 *
 * Alternative to `filter_var( $var, FILTER_VALIDATE_BOOLEAN )`.
 *
 * @since 4.0.0
 *
 * @param mixed $var Boolean value to validate.
 * @return bool Whether the value is validated.
 */
function wp_validate_boolean( $var ) {
    if ( is_bool( $var ) ) {
        return $var;
    }

    if ( is_string( $var ) && 'false' === strtolower( $var ) ) {
        return false;
    }

    return (bool) $var;
}

/**
 * Delete a file
 *
 * @since 4.2.0
 *
 * @param string $file The path to the file to delete.
 */
function wp_delete_file( $file ) {
    /**
     * Filters the path of the file to delete.
     *
     * @since 2.1.0
     *
     * @param string $medium Path to the file to delete.
     */
    $delete = apply_filters( 'wp_delete_file', $file );
    if ( ! empty( $delete ) ) {
        @unlink( $delete );
    }
}

/**
 * Outputs a small JS snippet on preview tabs/windows to remove `window.name` on unload.
 *
 * This prevents reusing the same tab for a preview when the user has navigated away.
 *
 * @since 4.3.0
 */
function wp_post_preview_js() {
    global $post;

    if ( ! is_preview() || empty( $post ) ) {
        return;
    }

    // Has to match the window name used in post_submit_meta_box()
    $name = 'wp-preview-' . (int) $post->ID;

    ?>
    <script>
        ( function() {
            var query = document.location.search;

            if ( query && query.indexOf( 'preview=true' ) !== -1 ) {
                window.name = '<?php echo $name; ?>';
            }

            if ( window.addEventListener ) {
                window.addEventListener( 'unload', function() { window.name = ''; }, false );
            }
        }());
    </script>
    <?php
}

/**
 * Parses and formats a MySQL datetime (Y-m-d H:i:s) for ISO8601/RFC3339.
 *
 * Explicitly strips timezones, as datetimes are not saved with any timezone
 * information. Including any information on the offset could be misleading.
 *
 * @since 4.4.0
 *
 * @param string $date_string Date string to parse and format.
 * @return string Date formatted for ISO8601/RFC3339.
 */
function mysql_to_rfc3339( $date_string ) {
    $formatted = mysql2date( 'c', $date_string, false );

    // Strip timezone information
    return preg_replace( '/(?:Z|[+-]\d{2}(?::\d{2})?)$/', '', $formatted );
}

/**
 * Attempts to raise the PHP memory limit for memory intensive processes.
 *
 * Only allows raising the existing limit and prevents lowering it.
 *
 * @since 4.6.0
 *
 * @param string $context Optional. Context in which the function is called. Accepts either 'admin',
 *                        'image', or an arbitrary other context. If an arbitrary context is passed,
 *                        the similarly arbitrary {@see '{$context}_memory_limit'} filter will be
 *                        invoked. Default 'admin'.
 * @return bool|int|string The limit that was set or false on failure.
 */
function wp_raise_memory_limit( $context = 'admin' ) {
    // Exit early if the limit cannot be changed.
    if ( false === wp_is_ini_value_changeable( 'memory_limit' ) ) {
        return false;
    }

    $current_limit     = @ini_get( 'memory_limit' );
    $current_limit_int = wp_convert_hr_to_bytes( $current_limit );

    if ( -1 === $current_limit_int ) {
        return false;
    }

    $wp_max_limit     = WP_MAX_MEMORY_LIMIT;
    $wp_max_limit_int = wp_convert_hr_to_bytes( $wp_max_limit );
    $filtered_limit   = $wp_max_limit;

    switch ( $context ) {
        case 'admin':
            /**
             * Filters the maximum memory limit available for administration screens.
             *
             * This only applies to administrators, who may require more memory for tasks
             * like updates. Memory limits when processing images (uploaded or edited by
             * users of any role) are handled separately.
             *
             * The `WP_MAX_MEMORY_LIMIT` constant specifically defines the maximum memory
             * limit available when in the administration back end. The default is 256M
             * (256 megabytes of memory) or the original `memory_limit` php.ini value if
             * this is higher.
             *
             * @since 3.0.0
             * @since 4.6.0 The default now takes the original `memory_limit` into account.
             *
             * @param int|string $filtered_limit The maximum WordPress memory limit. Accepts an integer
             *                                   (bytes), or a shorthand string notation, such as '256M'.
             */
            $filtered_limit = apply_filters( 'admin_memory_limit', $filtered_limit );
            break;

        case 'image':
            /**
             * Filters the memory limit allocated for image manipulation.
             *
             * @since 3.5.0
             * @since 4.6.0 The default now takes the original `memory_limit` into account.
             *
             * @param int|string $filtered_limit Maximum memory limit to allocate for images.
             *                                   Default `WP_MAX_MEMORY_LIMIT` or the original
             *                                   php.ini `memory_limit`, whichever is higher.
             *                                   Accepts an integer (bytes), or a shorthand string
             *                                   notation, such as '256M'.
             */
            $filtered_limit = apply_filters( 'image_memory_limit', $filtered_limit );
            break;

        default:
            /**
             * Filters the memory limit allocated for arbitrary contexts.
             *
             * The dynamic portion of the hook name, `$context`, refers to an arbitrary
             * context passed on calling the function. This allows for plugins to define
             * their own contexts for raising the memory limit.
             *
             * @since 4.6.0
             *
             * @param int|string $filtered_limit Maximum memory limit to allocate for images.
             *                                   Default '256M' or the original php.ini `memory_limit`,
             *                                   whichever is higher. Accepts an integer (bytes), or a
             *                                   shorthand string notation, such as '256M'.
             */
            $filtered_limit = apply_filters( "{$context}_memory_limit", $filtered_limit );
            break;
    }

    $filtered_limit_int = wp_convert_hr_to_bytes( $filtered_limit );

    if ( -1 === $filtered_limit_int || ( $filtered_limit_int > $wp_max_limit_int && $filtered_limit_int > $current_limit_int ) ) {
        if ( false !== @ini_set( 'memory_limit', $filtered_limit ) ) {
            return $filtered_limit;
        } else {
            return false;
        }
    } elseif ( -1 === $wp_max_limit_int || $wp_max_limit_int > $current_limit_int ) {
        if ( false !== @ini_set( 'memory_limit', $wp_max_limit ) ) {
            return $wp_max_limit;
        } else {
            return false;
        }
    }

    return false;
}

/**
 * Generate a random UUID (version 4).
 *
 * @since 4.7.0
 *
 * @return string UUID.
 */
function wp_generate_uuid4() {
    return sprintf( '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
        mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ),
        mt_rand( 0, 0xffff ),
        mt_rand( 0, 0x0fff ) | 0x4000,
        mt_rand( 0, 0x3fff ) | 0x8000,
        mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff )
    );
}

/**
 * Get last changed date for the specified cache group.
 *
 * @since 4.7.0
 *
 * @param $group Where the cache contents are grouped.
 *
 * @return string $last_changed UNIX timestamp with microseconds representing when the group was last changed.
 */
function wp_cache_get_last_changed( $group ) {
    $last_changed = wp_cache_get( 'last_changed', $group );

    if ( ! $last_changed ) {
        $last_changed = microtime();
        wp_cache_set( 'last_changed', $last_changed, $group );
    }

    return $last_changed;
}
